Yersinia spp.来源植酸酶的酶学性质及结构与功能研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
植酸是豆类、谷类等作物种子中磷的主要储存形式。植酸酶(肌醇六磷酸磷酸水解酶)能够水解植酸的磷酸单酯键生成无机磷和磷酸肌醇衍生物。单胃动物饲料中添加微生物来源植酸酶能够有效地提高植酸磷的利用效率、降低动物排泄物中的磷污染,并能通过去除植酸的抗营养作用来提高饲料的营养价值。对具有高比活、良好热稳定性和酸稳定性植酸酶的需求,促进了新酶资源的开发以及酶的催化机制研究和蛋白质工程研究。
     HAP植酸酶(EC 3.1.3.8)由于其优良的催化性质而被广泛应用于动物饲料添加剂。Yersinia spp.是优良HAP植酸酶的主要来源,本实验室先后从Yersinia属11个种的基因组中克隆得到了10个HAP植酸酶基因,其中Yersinia intermedia、Y. rohdei来源的植酸酶具有良好的综合性质和潜在的应用价值。为了深入研究Yersinia spp.来源的植酸酶,本研究分别对Y. kristeensenii, Y.frederiksenii和Y. enterocolitica来源的三个植酸酶基因Ykappa, Yfappa和Yeappa进行了异源表达和性质研究,并通过定点突变对其相应的催化机制进行了研究。
     来源于Y. kristeensenii的植酸酶基因Ykappa在毕赤酵母中得到了活性表达。纯化的重组植酸酶YkAppa比活为2,656 U/mg (pH 4.5和37℃),在pH 4.5和55℃条件下酶活最高,并在pH 2.0–6.5均有植酸酶活性。YkAppa具有优良的pH稳定性,在pH 1.5–11.0,37℃条件下处理3 h后仍保留90%以上的酶活。YkAppa也具有良好的热稳定性,在80℃处理10 min后还剩余初始酶活的46%。在体外水解豆粕实验中,YkAppa表现出高效的植酸降解能力。与其他的植酸酶相比,YkAppa具有优良的综合性状,如比活高、pH稳定性和热稳定性好、豆粕中植酸降解率高等,从而具有一定的商业化潜力。
     在大肠杆菌中表达的重组植酸酶YfAppa最适pH为2.5—显著低于其他微生物来源植酸酶(最适pH 4.5–6.0)。YfAppa的氨基酸序列与Y. intermedia来源的HAP植酸酶(最适pH为4.5)一致性高达84%。通过对YfAppa与相关植酸酶进行氨基酸序列比对和结构建模,发现在YfAppa催化中心附近只有一个差异氨基酸。为了研究YfAppa的适酸性,本文通过定点突变构建了五个突变体(S51A,S51T,S51D,S51K和S51I),并对其在大肠杆菌中进行了表达、纯化和性质分析。Ser、Thr和Ile均为不带电荷的氨基酸,而相应的野生型和突变型植酸酶在最适pH方面表现出非常大的差异。突变体S51T和S51I的最适pH从2.5分别移到了4.5和5.0,确定了Ser51在YfAppapH特性中起关键作用。本研究发现了一个除静电荷之外的新的影响植酸酶pH特性的因子—活性中心附近氨基酸残基的侧链结构—对YfAppa的最适pH具有重要的影响。与野生型YfAppa相比,突变体S51T具有高比活、酸性范围内(pH 2.0–5.5)的高活性以及提高的热稳定性和酸稳定性等性质,从而具有潜在的商业价值。
     YeAppa在pH 5.0和45℃条件下酶活最高,其在生理温度条件下(pH 5.0和37℃)的比活为3.28 U/mg—为它同源植酸酶YkAppa (88%氨基酸序列一致性)比活的1/800。序列和结构比对分析显示YeAppa中的第79位氨基酸Arg79为非保守氨基酸,在YkAppa和其他HAP植酸酶中该氨基酸为Gly。YeAppa的R79G突变使其比活增加到2,615 U/mg,证明了Arg79为YeAppa低比活的原因。为了研究不同氨基酸残基在该位点对HAP植酸酶的影响,本文选择了晶体结构研究、性质研究很透彻的大肠杆菌植酸酶EcAppa为材料,将其相应位点的Gly73分别突变为Arg,Asp,Glu,Ser,Thr,Leu或Tyr。所有突变体的比活均低于野生型,并且随着氨基酸残基侧链体积的增大比活呈下降趋势,从而确定了一个新的影响HAP植酸酶比活的因素,即氨基酸残基侧链的体积。
     综上所述,Yersinia spp.来源的植酸酶在氨基酸序列上具有高度的一致性而在性质方面存在显著的差异,为植酸酶的结构与功能研究提供了优良材料。本文获得了一个具有优良综合性状并具有潜在商业价值的植酸酶YkAppa,确定了两个影响HAP植酸酶pH特性和催化效率的因子。因此,本研究具有重要的理论意义和实际应用价值。
Phytate is the primary storage form of phosphorus in cereals and legumes. Phytases (myo-inositolhexakisphosphate phosphohydrolases) hydrolyze the phosphoester bonds of phytate to yield inorganicphosphate and less-substituted inositol. Monogastric animal feed supplemented with microbial phytaseseffectively improves phytate phosphorus utilization, reduces the excretion of phosphorus in animalmanure and improves the nutrient value by removing the anti-nutrient factor of phytate in intensivelivestock production. The industrial demand for phytase with high specific activity, excellentthermostability and acid stability continues to stimulate the search for new enzyme sources and thestudies on the catalytic mechanisms and protein-engineering of phytases.
     HAP phytases (EC 3.1.3.8) are a class of phytases with excellent catalysis capacity and have beenwidely used in animal feed. Yersinia spp. are excellent microbial sources of HAP phytases,and ten HAPphytase genes have been cloned from 11 species genomes of the genus Yersinia. Among them, HAPphytases from Yersinia intermedia and Y. rohdei had excellent comprehensive properties and applicationpotential. In this study, we heterologously expressed and characterized the genes Ykappa, Yfappa andYeappa from Yersinia kristeensenii, Y. frederiksenii and Y. enterocolitica, respectively. Furthermore, thestudies on catalytic mechanisms through site-directed mutagenesis were conducted.
     The gene Ykappa from Y. kristeensenii was expressed in Pichia pastoris. The purified recombinantphytase, YkAppa, had optimal activity at 55℃and pH 4.5, exhibited enzymatic activity between pH 2.0and 6.5, with a specific activity of 2,656 U/mg at pH 4.5 and 37℃. YkAppa was highly pH stable,retaining more than 90% of its initial activity after pre-incubation under varying pH conditions (pH1.5–11.0) at 37℃for 3 h. YkAppa was thermostable, and retained 46% of its initial activity afterincubation at 80℃for 10 min. YkAppa also showed efficiency in hydrolysis of phytate phosphorusfrom soybean meal in vitro. Compared with other well-known phytases, YkAppa has excellentcomprehensive properties, such as high specific activity, good pH stability and thermostability, highdegradation efficacy of soybean meal phytate and so on, and has significant potential in feed industryuse.
     The purified YfAppa, heterologously expressed in Escherichia coli, had optimal activity at pH2.5—substantially lower than that of most of microbial phytases (pH optima 4.5–6.0). The amino acidsequence of YfAppa has the highest identity (84%) to that of Y. intermedia HAP phytase (optimal pH4.5). Based on sequence alignment and molecular modeling of YfAppa and related phytases, only onedivergent residue in YfAppa, Ser51, was identified to be in close proximity to the catalytic site. Tounderstand the acidic adaptation of YfAppa, five mutants (S51A, S51T, S51D, S51K and S51I) wereconstructed by site-directed mutagenesis, expressed in E. coli, purified, and characterized. Ser, Thr andIle are all uncharged amino acids, but replacing Ser with Thr and Ile changed the pH optima a lot.Mutants S51T and S51I exhibited a shift in the optimal pH from 2.5 to 4.5 and 5.0, respectively,confirming the role of Ser51 in defining the optimal pH. Thus, a previously unrecognized factor other than electrostatics—presumably the side-chain structure near the active site—contributes to the optimalpH for YfAppa activity. Compared with wild-type YfAppa, mutant S51T showed higher specificactivity, greater activity over pH 2.0–5.5, and increased thermal and acid stability. These propertiesmake mutant S51T a better candidate than the wild-type YfAppa for use in animal feed.
     The maximum activity of YeAppa occurs at pH 5.0 and 45℃, and notably its specific activityunder physiological conditions (3.28 U/mg, pH 5.0 and 37℃) is 800-fold less than that of its Y.kristeensenii homolog (YkAppa; 88% amino acid sequence identity). Sequence alignment andmolecular modeling showed that the arginine at position 79 (Arg79) in YeAppa corresponding to Gly inYkAppa as well as other HAP phytases is the only non-conserved residue near the catalytic site.Site-directed replacement of Arg79 with Gly increased the specific activity of YeAppa to 2,615 U/mg,indicating that Arg79 is primarily responsible for the decreased activity. To characterize the effects ofother residues at this position on the specific activities of phytases, E. coli EcAppa, a well-characterizedphytase with a known crystal structure, was selected for mutagenesis—its Gly73 was replaced with Arg,Asp, Glu, Ser, Thr, Leu, or Tyr. The specific activities of all of the corresponding EcAppa mutants wereless than that of the wild-type phytase, and the activity levels were approximately proportional to themolecular volumes of the substituted residues’side chains. Thus, a new determinant that influences thecatalytic efficiency of HAP phytases—the molecular volumes of the substituted residues’side chainshas been identified.
     In summary, phytases from Yersinia spp. are highly identical in amino acid sequences but varied inproperties, and are good materials for structure-function studies. This study obtained a phytase YkAppawith excellent comprehensive properties and important application potential, identified two factorscontributing to pH optima and catalytic efficiency of HAP phytases, and thus had great significance intheory and application.
引文
1 Abelson, P.H. A potential phosphate crisis. Science, 1999, 283: 2015.
    2 Anderson G.. Assessing organic phosphorus in soils. In: Khasawneh F.E., Sample E.C., Kamprath EJ., editors. The Role of Phosphorus in Agriculture. Madison, WI: Amer Soc Agronomy, 1980. pp. 411~431.
    3 Arnold, K., Bordoli, L., Kopp, J., Schwede, T. The SWISS-MODEL workspace: a web-based environment for protein structure homology modelling. Bioinformatics, 2006. 22: 195~201.
    4 Asada, K., Tanaka, K., Kasai, Z. Formation of phytic acid in cereal grains. Ann N Y Acad Sci, 1969, 165: 801~814.
    5 Asmar, F. Variation in activity of root extracellular phytase between genotypes of barley. Plant Soil, 1997, 195: 61~64.
    6 Bajwa, W., Meyhack, B., Rudolph, H., Schweingruber, A.M., Hinnen, A. Structural analysis of the two tandemly repeated acid phosphatase genes in yeast. Nucleic Acids Res, 1984, 12: 7721~7739.
    7 Barrientos, L., Scott, J.J., Murthy, P.P. Specificity of hydrolysis of phytic acid by alkaline phytase from lily pollen. Plant Physiol, 1994, 106: 1489~1495.
    8 Berridge, M.J., Irvine, R.F. Inositol trisphosphate, a novel second messenger in cellular signal transduction. Nature, 1984, 312: 315~321.
    9 Bindu, S., Somashekar, D., Joseph, R. A comparative study on permeabilization treatments for in situ determination of phytase of Rhodotoroula gracilis. Lett Appl Microbiol, 1998, 27: 336~340.
    10 Biswas, S., Maity, I.B., Chakrabarti, S., Biswas, B.B. Purification and characterization of myo-inositol hexaphosphate-adenosine diphosphate phosphotransferase from Phaseolus aureus. Arch Biochem Biophys, 1978, 85: 557~566.
    11 Bitar, K., Reinhold, J.G. Phytase and alkaline phosphatase activities in intestinal mucosae of rat, chicken, calf, and man. Biochim Biophys Acta, 1972, 68: 442~452.
    12 Brannigan, J.A., Wilkinson, A.J. Protein engineering 20 years on. Nat Rev Mol Cell Biol, 2002, 3: 964~970.
    13 Butterworth, A.C., Medrano, F.J., Eakin, A.E., Craig, S.P. Saturation mutagenesis, complement selection, and steady-state kinetic studies illuminate the roles of invariant residues in active site loop I of the hypoxanthine phosphoribosyltransferase from Trypanosoma cruzi. Biochim Biophys Acta, 2004, 699: 87~94.
    14 Cabahug, S., Ravindran, V., Selle, P.H., Bryden, W.L. Response of broiler chickens to microbial phytase supplementation as influenced by dietary phytic acid and non-phytate phosphorus contents. I. Effects on bird performance and toe ash. Br Poult Sci, 1999, 40: 660~666.
    15 Camden, B., Morel, P., Thomas, D., Ravindran, V., Bedford, M. Effectiveness of exogenous microbial phytase in improving the bioavailabilities of phosphorus and other nutrients in maize-soya-bean meal diets for broilers. Anim Sci, 2001, 73: 289~297.
    16 Casey, A., Walsh, G. Identification and characterization of a phytase of potential commercial interest. J Biotechnol, 2004, 110: 313~322.
    17 Chang, C.C., Chen, T.T., Cox, B.W., Dawes, G.N., Stemmer, W.P., Punnonen, J., Patten, P.A. Evolution of a cytokine using DNA family shuffling. Nat Biotechnol, 1999, 17: 793~797.
    18 Chen, Y.L., Tang, T.Y., Cheng, K.J. Directed evolution to produce an alkalophilic variant from a Neocallimastix patriciarum xylanase. Can J Microbiol, 2001, 47: 1088~1094.
    19 Cheryan, M. Phytic acid interactions in food systems. Crit Rev Food Sci Nutr, 1980, 13: 297~335.
    20 Chiang, L.W., Kovari, I., Howe, M.M. Mutagenic oligonucleotide-directed PCR amplification (Mod-PCR): an efficient method for generating random base substitution mutations in a DNA sequence element. PCR Methods Appl, 1993, 2: 210~217.
    21 Chiu, J., March, P.E., Lee, R., and Tillett, D. Site-directed, Ligase-Independent Mutagenesis (SLIM): a single-tube methodology approaching 100% efficiency in 4 h. Nucleic Acids Res, 2004, 32: e174.
    22 Cho, J.S., Lee, C.W., Kang, S.H., Lee, J.C., Bok, J.D., Moon, Y.S., Lee, H.G., Kim, S.C., Choi, Y.J. Purification and characterization of a phytase from Pseudomonas syringae MOK1. Curr Microbiol, 2003, 47: 290~294.
    23 Choi, Y.M., Suh, H.J., Kim, J.M. Purification and properties of extracellular phytase from Bacillus sp. KHU-10. J Protein Chem, 2001, 20: 287~292.
    24 Chu, H.M., Guo, R.T., Lin, T.W., Chou, C.C., Shr, H.L., Lai, H.L., Tang, T.Y., Cheng, K.J., Selinger, B.L., Wang, A.H. Structures of Selenomonas ruminantium phytase in complex with persulfated phytate: DSP phytase fold and mechanism for sequential substrate hydrolysis. Structure, 2004, 12: 2015~2024.
    25 Common, F. Biological availability of phosphorus for pigs. Nature, 1989, 143: 370~380.
    26 Cosgrove, D. The chemistry and biochemistry of inositol polyphosphates. Rev Pure Appl Chem, 1966, 16: 209~215.
    27 Cosgrove, D. Phytases and intermediates in the dephosphorylation of P6-inositols by phytase enzymes. In: Cosgrove D.J. editor. Inositol phosphates: their chemistry, biochemistry, and physiology. Amsterdam: Elsevere, 1980. pp 85~105.
    28 Cosgrove, D.J. Ion-exchange chromatography of inositol polyphosphates. Ann N Y Acad Sci, 1969, 165: 677~686.
    29 Cosgrove, D.J. Inositol phosphates of microbial origin. Inositol phosphate intermediates in the dephosphorylation of the hexaphosphates of myoinositol, scyllo-inositol, and D-chiro-inositol by a bacterial (Pseudomonas sp.) phytase. Austral J Biol Sci, 1970, 23: 1207~1220.
    30 Cowieson, A.J., Acamovic, T., Bedford, M.R. The effects of phytase and phytic acid on the loss of endogenous amino acids and minerals from broiler chickens. Br Poult Sci, 2004, 45: 101~108.
    31 Cowieson, A.J., Ravindran, V., and Selle, P.H. 2008. Influence of dietary phytic acid and source of microbial phytase on ileal endogenous amino acid flows in broiler chickens. Poult Sci, 87: 2287~2299.
    32 Cromwell, G.L., Coffey, R.D., Monegue, H.J., Randolph, J.H. Efficacy of low-activity, microbial phytase in improving the bioavailability of phosphorus in corn-soybean meal diets for pigs. J Anim Sci, 1995, 73: 449~456.
    33 Dasgupta, S., Dasgupta, D., Sen, M., Biswas, S., Biswas, B.B. Interaction of myoinositoltrisphosphate-phytase complex with the receptor for intercellular Ca2+ mobilization in plants. Biochemistry, 1996, 35: 4994~5001.
    34 Dassa, E., Boquet, P.L. Identification of the gene appA for the acid phosphatase (pH optimum 2.5) of Escherichia coli. Mol Gen Genet, 1985, 200: 68~73.
    35 Dassa, J., Marck, C., Boquet, P.L. The complete nucleotide sequence of the Escherichia coli gene appA reveals significant homology between pH 2.5 acid phosphatase and glucose-1-phosphatase. J Bacteriol, 1990, 172: 5497~5500.
    36 Day, P.R. Genetic modification of plants: significant issues and hurdles to success. Am J Clin Nutr, 1996, 63: 651S~656S.
    37 de Boland, A.R., Garner, G.B., O'Dell, B.L. Identification and properties of "phytate" in cereal grains and oilseed products. J Agric Food Chem, 1975, 23: 1186~1189.
    38 Denu, J.M., Dixon, J.E. Protein tyrosine phosphatases: mechanisms of catalysis and regulation. Curr Opin Chem Biol, 1998, 2: 633~641.
    39 Dvorakova, J., Kopecky, J., Havlicek, V., Kren, V. Formation of myo-inositol phosphates by Aspergillus niger 3-phytase. Folia Microbiol (Praha), 2000, 45: 128~132.
    40 Ebrahimnezhad, Y., Shivazad, M., Taherkhani, R., Nazeradl, K. Effects of ethylenediaminetetraacetic acid on phytate phosphorus utilization and efficiency of microbial phytase in broiler chicks. J Anim Physiol Anim Nutr (Berl), 2008, 92: 168~172.
    41 Ehrlich, K.C., Montalbano, B.G., Mullaney, E.J., Dischinger, H.C., Jr., Ullah, A.H. Identification and cloning of a second phytase gene (phyB) from Aspergillus niger (ficuum). Biochem Biophys Res Commun, 1993, 195: 53~57.
    42 Elliott, S., Chang, C.W., Schweingruber, M.E., Schaller, J., Rickli, E.E., Carbon, J. Isolation and characterization of the structural gene for secreted acid phosphatase from Schizosaccharomyces pombe. J Biol Chem, 1986, 261: 2936~2941.
    43 Fang, T.Y., Ford, C. Protein engineering of Aspergillus awamori glucoamylase to increase its pH optimum. Protein Eng, 1998, 11: 383~388.
    44 Farrell, D.J. Recent Advances in Animal Nutrition in Australia. Armidale: University of New England, 1997: 136~114.
    45 Fritts, C., Waldroup, P. Modified phosphorus program for broilers based on commercial feeding intervals to sustain live performance and reduce total and water-soluble phosphorus in litter. J Appl Poult Res, 2006, 15: 207~218.
    46 Fu, D., Huang, H., Luo, H., Wang, Y., Yang, P., Meng, K., Bai, Y., Wu, N., Yao, B. A highly pH-stable phytase from Yersinia kristeensenii: Cloning, expression, and characterization. Enzyme Microb Technol, 2008, 42: 499~505.
    47 Fu, D., Huang, H., Meng, K., Wang, Y., Luo, H., Yang, P., Yuan, T., Yao, B. Improvement of Yersinia frederiksenii phytase performance by a single amino acid substitution. Biotechnol Bioeng, 2009, 103: 857~864.
    48 Geier, C., von Figura, K., Pohlmann, R. Molecular cloning of the mouse lysosomal acid phosphatase. Biol Chem Hoppe Seyler, 1991, 372: 301~304.
    49 George, T.S., Simpson, R.J., Hadobas, P.A., Richardson, A.E. Expression of a fungal phytase gene in Nicotiana tabacum improves phosphorus nutrition of plants grown in amended soils. Plant Biotechnol J, 2005, 3: 129~140.
    50 Gibson, D.M. Production of extracellular phytase from Aspergillusficuum on starch media. Biotechnology Letters, 1987, 9: 305~310.
    51 Golovan, S.P., Hayes, M.A., Phillips, J.P., Forsberg, C.W. Transgenic mice expressing bacterial phytase as a model for phosphorus pollution control. Nat Biotechnol, 2001a, 19: 429~433.
    52 Golovan, S.P., Meidinger, R.G., Ajakaiye, A., Cottrill, M., Wiederkehr, M.Z., Barney, D.J., Plante, C., Pollard, J.W., Fan, M.Z., Hayes, M.A., et al. Pigs expressing salivary phytase produce low-phosphorus manure. Nat Biotechnol, 2001b, 19: 741~745.
    53 Gordon, R., Roland DA, S. Influence of supplemental phytase on calcium and phosphorus utilization in laying hens. Poult Sci, 1998, 77: 290~294.
    54 Greiner, R., Alminger, M.L., Carlsson, N.G.. Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of baker's yeast. J Agric Food Chem, 2001, 49: 2228~2233.
    55 Greiner, R., Haller, E., Konietzny, U., Jany, K.D. Purification and characterization of a phytase from Klebsiella terrigena. Arch Biochem Biophys, 1997, 341: 201~206.
    56 Greiner, R., Konietzny, U. Endogenous phytate-degrading enzymes are responsible for phytate reduction while preparing beans (Phaseolus vulgaris). J Food Process Preserv, 1998, 22: 321~331.
    57 Greiner, R., Konietzny, U. Improving enzymatic reduction of myo-inositol phosphates with inhibitory effects on mineral absorption in black beans (Phaseolus vulgaris var. Preto). J Food Process Preserv, 1999, 23: 249~261.
    58 Greiner, R., Konietzny, U. Phytase for food application. Food Technol Biotechnol, 2006, 44: 125~140.
    59 Greiner, R., Konietzny, U., Jany, K.D. Purification and Characterization of Two Phytases from Escherichia coli. Arch Biochem Biophys, 1993, 303: 107~113.
    60 Guex, N., Peitsch, M.C. SWISS-MODEL and the Swiss-PdbViewer: an environment for comparative protein modeling. Electrophoresis, 1997, 18: 2714~2723.
    61 Ha, N.C., Oh, B.C., Shin, S., Kim, H.J., Oh, T.K., Kim, Y.O., Choi, K.Y., Oh, B.H. Crystal structures of a novel, thermostable phytase in partially and fully calcium-loaded states. Nat Struct Biol, 2000, 7: 147~153.
    62 Haefner, S., Knietsch, A., Scholten, E., Braun, J., Lohscheidt, M., Zelder, O. Biotechnological production and applications of phytases. Appl Microbiol Biotechnol, 2005, 68: 588~597.
    63 Hall, J.R., Hodges, T.K. Phosphorus metabolism of germinating oat seeds. Plant Physiol, 1966, 41: 1459~1464.
    64 Hamada, J. Isolation and identification of the multiple forms of soybean phytases. J Am Oil Chem Soc, 1996, 73: 1143~1151.
    65 Han, Y., Lei, X.G. Role of glycosylation in the functional expression of an Aspergillus niger phytase (phyA) in Pichia pastoris. Arch Biochem Biophys, 1999, 364: 83~90.
    66 Hara, A., Ebina, S., Kondo, A., Funagua, T. A new type of phytase from pollen of Typha latifolia L. Agric Biol Chem, 1985, 49: 3539~3544.
    67 Harrison, A. Soil Organic Phosphorus. A Review of World Literature. Wallingford, UK: CAB International, 1987.
    68 Hartig, T. Uber das Klebermehl. Botanische Z, 1885, 13: 881~885.
    69 Hayakawa, T., Toma, Y., Igaue, I. Purification and characterization of acid phosphatases with or without phytase activity from rice bran. Agric Biol Chem, 1989, 53: 1475~1483.
    70 Hayes, J., Simpson, R., Richardson, A. The growth and phosphorus tilization of plants in sterile media when supplied with inositol hexaphosphate, glucose-1-phosphate or inorganic phosphate. Plant Soil, 2000, 220: 165~174.
    71 Hegeman, C.E., Grabau, E.A. A novel phytase with sequence similarity to purple acid phosphatases is expressed in cotyledons of germinating soybean seedlings. Plant Physiol, 2001, 126: 1598~1608.
    72 Ho, S.N., Hunt, H.D., Horton, R.M., Pullen, J.K., Pease, L.R. Site-directed mutagenesis by overlap extension using the polymerase chain reaction. Gene, 1989, 77: 51~59.
    73 Hong, C.Y., Cheng, K.J., Tseng, T.H., Wang, C.S., Liu, L.F., Yu, S.M. Production of two highly active bacterial phytases with broad pH optima in germinated transgenic rice seeds. Transgenic Res, 2004, 13: 29~39.
    74 Huang, H., Luo, H., Yang, P., Meng, K., Wang, Y., Yuan, T., Bai, Y., Yao, B. A novel phytase with preferable characteristics from Yersinia intermedia. Biochem Biophys Res Commun, 2006, 350: 884~889.
    75 Hubel, F., Beck, E. Maize Root Phytase: Purification, Characterization, and Localization of Enzyme Activity and Its Putative Substrate. Plant Physiol, 1996, 112: 1429~1436.
    76 Hurrell, R.F., Reddy, M.B., Juillerat, M.A., Cook, J.D. Degradation of phytic acid in cereal porridges improves iron absorption by human subjects. Am J Clin Nutr, 2003, 77: 1213~1219.
    77 Idriss, E.E., Makarewicz, O., Farouk, A., Rosner, K., Greiner, R., Bochow, H., Richter, T., Borriss, R. Extracellular phytase activity of Bacillus amyloliquefaciens FZB45 contributes to its plant-growth-promoting effect. Microbiology, 2002, 148: 2097~2109.
    78 Iqbal, T.H., Lewis, K.O., Cooper, B.T. Phytase activity in the human and rat small intestine. Gut, 1994, 35: 1233~1236.
    79 Irving, G.C., Cosgrove, D.J. Inositol phosphate phosphatases of microbiological origin: the inositol pentaphosphate products of Aspergillus ficuum phytases. J Bacteriol, 1972, 112: 434~438.
    80 Irving, G.C., Cosgrave, D.J. inositol phosphate phosphatases of microbiological origin. Some properties of the partially purified phosphatases of Aspergillus ficuum NRRL 3135. Aust J Biol Sci, 1974, 27: 361~368.
    81 Jenuth, J.P. The NCBI. Publicly available tools and resources on the Web. Methods Mol Biol, 2000, 132: 301~312.
    82 Jermutus, L., Tessier, M., Pasamontes, L., van Loon, A.P., Lehmann, M. Structure-based chimeric enzymes as an alternative to directed enzyme evolution: phytase as a test case. J Biotechnol, 2001, 85: 15~24.
    83 Johnson, L.F., Tate, M.E. The structure of myo-inositol pentaphosphates. Ann N Y Acad Sci, 1969, 165: 526~532.
    84 Jongbloed, A.W., Mroz, Z., Kemme, P.A. The effect of supplementary Aspergillus niger phytase in diets for pigs on concentration and apparent digestibility of dry matter, total phosphorus, and phytic acid in different sections of the alimentary tract. J Anim Sci, 1992, 70: 1159~1168.
    85 Jonson, L., Tate, ME. The conformational analysis of phytic acid based on NMR spectra. J Chem, 1969, 47: 63~73.
    86 Jurgens, M. Animal feeding and nutrition. Iowa: Kendall/Hunt; 1997.
    87 Kasim, A.B., Edwards, H.M. The analysis for inositol phosphate forms in feed ingredients. J Sci Food Agric, 1998, 76: 1~9.
    88 Kegler-Ebo, D.M., Polack, G.W., DiMaio, D. Use of codon cassette mutagenesis for saturation mutagenesis. Methods Mol Biol, 1996, 57: 297~310.
    89 Kerovuo, J., Lauraeus, M., Nurminen, P., Kalkkinen, N., Apajalahti, J. Isolation, characterization, molecular gene cloning, and sequencing of a novel phytase from Bacillus subtilis. Appl Environ Microbiol, 1998, 64: 2079~2085.
    90 Kerovuo, J., Rouvinen, J., Hatzack, F. Analysis of myo-inositol hexakisphosphate hydrolysis by Bacillus phytase: indication of a novel reaction mechanism. Biochem J, 2000, 352: 623~628.
    91 Kerovuo, J., Tynkkynen, S. Expression of Bacillus subtilis phytase in Lactobacillus plantarum 755. Lett Appl Microbiol, 2000, 30: 325~329.
    92 Kim, J.H., Choi, G.S., Kim, S.B., Kim, W.H., Lee, J.Y., Ryu, Y.W., Kim, G.J. Enhanced thermostability and tolerance of high substrate concentration of an esterase by directed evolution. J Mol Catal B Enzym, 2004, 27: 169~175.
    93 Kim, T., Mullaney, E.J., Porres, J.M., Roneker, K.R., Crowe, S., Rice, S., Ko, T., Ullah, A.H., Daly, C.B., Welch, R., et al. Shifting the pH profile of Aspergillus niger PhyA phytase to match the stomach pH enhances its effectiveness as an animal feed additive. Appl Environ Microbiol, 2006, 72: 4397~4403.
    94 Kim, Y.O., Kim, H.K., Bae, K.S., Yu, J.H., Oh, T.K. Purification and properties of a thermostable phytase from Bacillus sp. DS11. Enzyme Microb Technol, 1998a, 22: 2~7.
    95 Kim, Y.O., Lee, J.K., Kim, H.K., Yu, J.H., Oh, T.K. Cloning of the thermostable phytase gene (phy) from Bacillus sp. DS11 and its overexpression in Escherichia coli. FEMS Microbiol Lett, 1998b,162: 185~191.
    96 Kong, F., Lin, W., Yan, X., Liao, H. Phytate-phosphorus uptake and utilization by transgenic tobacco carrying Bacillus subtilis phytase gene. Ying Yong Sheng Tai Xue Bao, 2005, 16: 2389~2393.
    97 Konietzny, U., Greiner, R. Molecular and catalytic properties of phytate-degrading enzymes (phytases). Int J Food SciTechnol, 2002, 37: 791~812.
    98 Kostrewa, D., Gruninger-Leitch, F., D'Arcy, A., Broger, C., Mitchell, D., van Loon, A.P. Crystal structure of phytase from Aspergillus ficuum at 2.5 ? resolution. Nat Struct Biol, 1997, 4: 185~190.
    99 Kostrewa, D., Wyss, M., D'Arcy, A., van Loon, A.P. Crystal structure of Aspergillus niger pH 2.5 acid phosphatase at 2. 4 A resolution. J Mol Biol, 1999, 288: 965~974.
    100 Krishna, C., and Nokes, S.E. 2001. Predicting vegetative inoculum performance to maximize phytase production in solid-state fermentation using response surface methodology. J Ind Microbiol Biotechnol, 26: 161~170.
    101 Kunst, F., Ogasawara, N., Moszer, I., Albertini, A.M., Alloni, G., Azevedo, V., Bertero, M.G., Bessieres, P., Bolotin, A., Borchert, S., et al. The complete genome sequence of the gram-positive bacterium Bacillus subtilis. Nature, 1997, 390: 249~256.
    102 Larsson, M., Sandberg, A.S. Malting of oats in a pilot-plant process. Effects of heat treatment, storage and soaking conditions on phytate reduction. J Cereal Sci, 1995, 21: 87~95.
    103 Lehmann, M., Loch, C., Middendorf, A., Studer, D., Lassen, S.F., Pasamontes, L., van Loon, A.P., Wyss, M. The consensus concept for thermostability engineering of proteins: further proof of concept. Protein Eng, 2002, 15: 403~411.
    104 Lehmann, M., Lopez-Ulibarri, R., Loch, C., Viarouge, C., Wyss, M., van Loon, A.P. Exchanging the active site between phytases for altering the functional properties of the enzyme. Protein Sci, 2000, 9: 1866~1872.
    105 Lei, X., Porres, J., Mullaney, E., Brinch-Pedersen, H. Industrial Enzymes: Source, Structure and Application. Netherlands: Springer, 2007: 505~529.
    106 Lei, X.G., Porres, J.M. Phytase enzymology, applications, and biotechnology. Biotechnol Lett, 2003, 25: 1787~1794.
    107 Li, J., Hegeman, C.E., Hanlon, R.W., Lacy, G.H., Denbow, M.D., Grabau, E.A. Secretion of active recombinant phytase from soybean cell-suspension cultures. Plant Physiol, 1997, 114: 1103~1111.
    108 Li, J., Li, C., Xiao, W., Yuan, D., Wan, G., Ma, L. Site-directed mutagenesis by combination of homologous recombination and Dpn I digestion of the plasmid template in Escherichia coli. Anal Biochem, 2008, 373: 389~391.
    109 Li, M., Osaki, M., Rao, I., Tadano, T. Secretion of phytase from the roots of several plant species under phosphorus-deficient conditions. Plant Soil, 1997, 95: 161~169.
    110 Lim, D., Golovan, S., Forsberg, C.W., Jia, Z. Crystal structures of Escherichia coli phytase and its complex with phytate. Nat Struct Biol, 2000, 7: 108~113.
    111 Lindqvist, Y., Schneider, G., Vihko, P. Crystal structures of rat acid phosphatase complexed with the transition-state analogs vanadate and molybdate. Implications for the reaction mechanism. Eur J Biochem, 1994, 221: 139~142.
    112 Liu, N., Liu, G.H., Li, F.D., Sands, J.S., Zhang, S., Zheng, A.J., Ru, Y.J. Efficacy of phytases on egg production and nutrient digestibility in layers fed reduced phosphorus diets. Poult Sci, 2007, 86: 2337~2342.
    113 Lonnerdal, B., Bell, J.G., Hendrickx, A.G., Burns, R.A., Keen, C.L. Effect of phytate removal on zinc absorption from soy formula. Am J Clin Nutr, 1988, 48: 1301~1306.
    114 Lott1, J.N.A., Ockenden, I., Raboy, V., Batten, G.D. Phytic acid and phosphorus in crop seeds and fruits: a global estimate. Seed Sci Res, 2000, 10: 11~33.
    115 Lucca, P., Hurrell, R., Potrykus, I. Genetic engineering approaches to improve the bioavailability and the level of iron in rice grains. Theor Appl Genet, 2001, 102: 392~397.
    116 Lung, S., Lim, B. Assimilation of phytate-phosphorus by the extracellular phytase activity of tobacco (Nicotiana tabacum) is affected by the availability of soluble phytate. Plant Soil, 2006, 279: 187~199.
    117 Lung, S.C., Leung, A., Kuang, R., Wang, Y., Leung, P., Lim, B.L. Phytase activity in tobacco (Nicotiana tabacum) root exudates is exhibited by a purple acid phosphatase. Phytochemistry, 2008, 69: 365~373.
    118 Maenz, D., Engele-Schaan, CM, Newkirk, RW, Classen, HL. The effect of minerals and mineral chelators on the formation of phytase-resistant and phytase-susceptible forms of phytic acid in solution and in a slurry of canola meal. Anim Feed Sci Technol, 1999, 81: 177~192.
    119 Martin, C.J., Evans, W.J. Phytic acid-metal ion interactions. II. The effect of pH on Ca(II) binding. J Inorg Biochem, 1986, 27: 17~30.
    120 Maugenest, S., Martinez, I., Godin, B., Perez, P., Lescure, A.M Structure of two maize phytase genes and their spatio-temporal expression during seedling development. Plant Mol Biol, 1999, 39:
    503~514.
    121 Mayer, A.F., Hellmuth, K., Schlieker, H., Lopez-Ulibarri, R., Oertel, S., Dahlems, U., Strasser, A.W., van Loon, A.P. An expression system matures: a highly efficient and cost-effective process for phytase production by recombinant strains of Hansenula polymorpha. Biotechnol Bioeng, 1999, 63: 373~381.
    122 McClung, J.P., Stahl, C.H., Marchitelli, L.J., Morales-Martinez, N., Mackin, K.M., Young, A.J., Scrimgeour, A.G. Effects of dietary phytase on body weight gain, body composition and bone strength in growing rats fed a low-zinc diet. J Nutr Biochem, 2006, 17: 190~196.
    123 McCollum, E., Hart, EB. On the occurrence of a phytin splitting enzyme in animal tissue. J Biol Chem, 1908, 4: 497~500.
    124 Michell, R.H. Inositol phospholipids and cell surface receptor function. Biochim Biophys Acta, 1975, 415: 81~47.
    125 Mitchell, D.B., Vogel, K., Weimann, B.J., Pasamontes, L., van Loon, A.P. The phytase subfamily ofhistidine acid phosphatases: isolation of genes for two novel phytases from the fungi Aspergillus terreus and Myceliophthora thermophila. Microbiology, 1997, 143 ( Pt 1): 245~252.
    126 Mohanna, C., Nys, Y. Changes in zinc and manganese availability in broiler chicks induced by vegetal and microbial phytases. Anim Feed Sci Technol, 1999, 77: 241~253.
    127 Mullaney, E.J., Daly, C.B., Ehrlich, K.C., Ullah, A.H. The Aspergillus niger (ficuum) a phA gene encodes a pH 6.0-optimum acid phosphatase. Gene, 1995, 162: 117~121.
    128 Mullaney, E.J., Daly, C.B., Kim, T., Porres, J.M., Lei, X.G., Sethumadhavan, K., Ullah, A.H. Site-directed mutagenesis of Aspergillus niger NRRL 3135 phytase at residue 300 to enhance catalysis at pH 4.0. Biochem Biophys Res Commun, 2002, 297: 1016~1020.
    129 Mullaney, E.J., Daly, C.B., Ullah, A.H. Advances in phytase research. Adv Appl Microbiol, 2000, 47: 157~199.
    130 Mullaney, E.J., Ullah, A.H. Conservation of the active site motif in Aspergillus niger (ficuum) pH
    6.0 optimum acid phosphatase and kidney bean purple acid phosphatase. Biochem Biophys Res Commun, 1998, 243: 471~473.
    131 Murry, A.C., Lewis, R.D., Amos, H.E. The effect of microbial phytase in a pearl millet-soybean meal diet on apparent digestibility and retention of nutrients, serum mineral concentration, and bone mineral density of nursery pigs. J Anim Sci, 1997, 75: 1284~1291.
    132 Mwachireya, S.A., Beames, R.M., Higgs, D.A., Dosanjh, B.S. Digestibility of canola protein products derived from the physical, enzymatic and chemical processing of commercial canola meal in rainbow trout Oncorhynchus mykiss (Walbaum) held in fresh water. Aquacul Nutr, 1999, 5: 73~82.
    133 Myers, M.A., Healy, M.J., Oakeshott, J.G. Effects of the residue adjacent to the reactive serine on the substrate interactions of Drosophila esterase 6. Biochem Genet, 1993, 31: 259~278.
    134 Nagai, Y., Funahashi, S. Phytase (myo-inositol hexaphosphate phosphohydrolase) from wheat bran. Agric Biol Chem, 1962, 26: 794~803.
    135 Nakano, T., Joh, T., Tokumoto, E., Hayakawa, T. Purification and characterization of phytase from bran of Triticum aestivum L. Cv. Nourin #61. Food Sci Technol Res, 1999, 18: 18~23.
    136 Nayeem, A., Chiang, S.J., Liu, S.W., Sun, Y., You, L., Basch, J. Engineering enzymes for improved catalytic efficiency: a computational study of site mutagenesis in epothilone-B hydroxylase. Protein Eng Des Sel, 2009, 22: 257~266.
    137 Nelson, T.S., Shieh, T.R., Wodzinski, R.J., Ware, J.H. The availability of phytate phosphorus in soybean meal before and after treatment with a mold phytase. Poult Sci, 1968, 47: 1842~1848.
    138 Nelson, T.S., Shieh, T.R., Wodzinski, R.J., Ware, J.H. Effect of supplemental phytase on the utilization of phytate phosphorus by chicks. J Nutr, 1971, 101: 1289~1293.
    139 Oh, B.C., Chang, B.S., Park, K.H., Ha, N.C., Kim, H.K., Oh, B.H., Oh, T.K. Calcium-dependent catalytic activity of a novel phytase from Bacillus amyloliquefaciens DS11. Biochemistry, 2001, 40: 9669~9676.
    140 Oh, B.C., Choi, W.C., Park, S., Kim, Y.O., Oh, T.K. Biochemical properties and substratespecificities of alkaline and histidine acid phytases. Appl Microbiol Biotechnol, 2004, 63: 362~372.
    141 Olczak, M., Morawiecka, B., Watorek, W. Plant purple acid phosphatases - genes, structures and biological function. Acta Biochim Pol, 2003, 50: 1245~1256.
    142 Onyango, E.M., Bedford, M.R., Adeola, O. Efficacy of an evolved Escherichia coli phytase in diets of broiler chicks. Poult Sci, 2005, 84: 248~255.
    143 Ostanin, K., Van Etten, R.L. Asp304 of Escherichia coli acid phosphatase is involved in leaving group protonation. J Biol Chem, 1993, 268: 20778~20784.
    144 Ostermeier, M. Theoretical distribution of truncation lengths in incremental truncation libraries. Biotechnol Bioeng, 2003, 82: 564~577.
    145 Ostermeier, M., Lutz, S. The creation of ITCHY hybrid protein libraries. Methods Mol Biol, 2003, 231: 129~141.
    146 Pasamontes, L., Haiker, M., Henriquez-Huecas, M., Mitchell, D.B., van Loon, A.P. Cloning of the phytases from Emericella nidulans and the thermophilic fungus Talaromyces thermophilus. Biochim Biophys Acta, 1997a, 1353: 217~223.
    147 Pasamontes, L., Haiker, M., Wyss, M., Tessier, M., van Loon, A.P. Gene cloning, purification, and characterization of a heat-stable phytase from the fungus Aspergillus fumigatus. Appl Environ Microbiol, 1997b, 63: 1696~1700.
    148 Pen, J., Verwoerd, T.C., van Paridon, P.A., Beudeker, R.F., van den Elzen, P.J.M., Geerse, K., van der Klis, J.D., Versteegh, H.A.J., van Ooyen, A.J.J., Hoekema, A. Phytase-containing transgenic seeds as a novel feed additive for improved phosphorus utilization. Nat Biotech, 1993, 11: 811~814.
    149 Piddington, C.S., Houston, C.S., Paloheimo, M., Cantrell, M., Miettinen-Oinonen, A., Nevalainen, H., Rambosek, J. The cloning and sequencing of the genes encoding phytase (phy) and pH 2.5-optimum acid phosphatase (aph) from Aspergillus niger var. awamori. Gene, 1993, 133: 55~62.
    150 Pintar, J., Bujan, M., Homen, B., Gazic, K., Sikiric, M., Cerny, T. Effects of supplemental phytase on the mineral content in tibia of broilers fed different cereal based diets. Czech J Anim Sci, 2005, 50: 68~73.
    151 Pohlmann, R., Krentler, C., Schmidt, B., Schroder, W., Lorkowski, G., Culley, J., Mersmann, G., Geier, C., Waheed, A., Gottschalk, S., et al. Human lysosomal acid phosphatase: cloning, expression and chromosomal assignment. EMBO J, 1988, 7: 2343~2350.
    152 Powar, V.K., Jagannathan, V. Purification and properties of phytate-specific phosphatase from Bacillus subtilis. J Bacteriol, 1982, 151: 1102~1108.
    153 Quan, C.S., Tian, W.J., Fan, S.D., Kikuchi, J. Purification and properties of a low-molecular-weight phytase from Cladosporium sp. FP-1. J Biosci Bioeng, 2004, 97: 260~266.
    154 Ragon, M., Hoh, F., Aumelas, A., Chiche, L., Moulin, G., Boze, H. Structure of Debaryomyces castellii CBS 2923 phytase. Acta Crystallogr Sect F Struct Biol Cryst Commun, 2009, 65: 321~326.
    155 Rapoport, S., Leva, E, Guest, GM. Phytase in plasma and erythrocytes of vertebrates. J Biol Chem, 1941, 139: 621~632.
    156 Ravindran, V. Phytases in poultry nutrition: An overview. Proc Aust Poult Sci Symp, 1995, 7: 135~139.
    157 Ravindran, V., Bryden, W., Kornegay, E. Phytates: occurrence, bioavailability and implications in poultry nutrition. Poult Avian Biol Rev, 1995, 6: 125~143.
    158 Ravindran, V., Cabahug, S., Ravindra, G., Selle, P.H., Bryden, W.L. Response of broiler chickens to microbial phytase supplementation as influenced by dietary phytic acid and non-phytate phosphorous levels. II. Effects on apparent metabolisable energy, nutrient digestibility and nutrient retention. Br Poult Sci, 2000, 41: 193~200.
    159 Ravindran, V., Morel, P.C.H., Partridge, G.G., Hruby, M., Sands, J.S. Influence of an E. coli-derived phytases on nutrient utilization in broiler starter fed diets containing varying concentrations of phytic acid. Poult Sci, 2006, 85: 82~89.
    160 Reddy, N.R., Sathe, S.K., Salunkhe, D.K. Phytates in legumes and cereals. Adv Food Res, 1982, 28: 1~92.
    161 Richardson, A., Hadobas, P., Hayes, J. Acid phosphomonoesterase and phytase activities of wheat (Triticum aestivum L.) roots and utilization of organic phosphorus substrates by seedlings grown in sterile culture. Plant Cell Environ, 2000, 23: 397~405.
    162 Richardson, A., Hadobas, P., Hayes, J., O’Hara, C., Simpson, R. Utilization of phosphorus by pasture plants supplied with myo-inositol hexaphosphate is enhanced by the presence of soil micro-organisms. Plant Soil, 2001, 229: 47~56.
    163 Rodriguez, E., Mullaney, E.J., Lei, X.G. Expression of the Aspergillus fumigatus phytase gene in Pichia pastoris and characterization of the recombinant enzyme. Biochem Biophys Res Commun, 2000a, 268: 373~378.
    164 Rodriguez, E., Wood, Z.A., Karplus, P.A., Lei, X.G. Site-directed mutagenesis improves catalytic efficiency and thermostability of Escherichia coli pH 2.5 acid phosphatase/phytase expressed in Pichia pastoris. Arch Biochem Biophys, 2000b, 382: 105~112.
    165 Rumsey, G.L. Fish meal and alternate sourcesof protein in fish feeds: Update. Fisheries, 1993, 18: 14~19.
    166 Samanta, S., Dalal, B., Biswas, S., Biswas, B. Myoinositol trisphosphate-phytase complex as an elicitor in calcium mobilization in plants. Biochem Biophys Res Commun, 1993, 191: 427~434.
    167 Sandberg, A.S., Andersson, H. Effect of dietary phytase on the digestion of phytate in the stomach and small intestine of humans. J Nutr, 1988, 118: 469~473.
    168 Sandberg, A.S., Brune, M., Carlsson, N.G., Hallberg, L., Skoglund, E., Rossander-Hulthen, L. Inositol phosphates with different numbers of phosphate groups influence iron absorption in humans. Am J Clin Nutr, 1999, 70: 240~246.
    169 Schenk, G., Guddat, L.W., Ge, Y., Carrington, L.E., Hume, D.A., Hamilton, S., de Jersey, J.Identification of mammalian-like purple acid phosphatases in a wide range of plants. Gene, 2000, 250: 117~125.
    170 Schneider, G., Lindqvist, Y., Vihko, P. Three-dimensional structure of rat acid phosphatase. EMBO J, 1993, 12: 2609~2615.
    171 Schroder, B., Breves, G., Rodehutscord, M. Mechanisms of intestinal phosphorus absorption and availability of dietary phosphorus in pigs. Dtsch Tierarztl Wochenschr, 1996, 103: 209~214.
    172 Scott, J.J. Alkaline phytase activity in nonionic detergent extracts of legume seeds. Plant Physiol, 1991, 95: 1298~1301.
    173 Scott, J.J., Loewus, F.A. A Calcium-activated phytase from pollen of Lilium longiflorum. Plant Physiol, 1986, 82: 333~335.
    174 Sebastian, S., Touchburn, S., Chavez, E. Implications of phytic acid and supplemental microbial phytase in poultry nutrition: a review. World’s Poult Sci, 1998, J 54: 27~47.
    175 Segueilha, L., Lambrechts, C., Boze, H., Moulin, G., Galzy, P. Purification and properties of the phytase from Schwanniomyces castellii. J Ferment Bioeng, 1992, 74: 7~11.
    176 Selle, P.H. The potential of microbial phytase for the sustainable production of pigs and poultry: an Australian perspective. In: Korean Society of Animal Nutrition and Feedstuffs. Sevent Short Course on Feed Techonology, Korea: Ansung, 1997, 97: 1~39.
    177 Selle, P.H., Cadogan, D.J., Bryden, W.L. Effects of phytase supplementation of phosphorus-adequate, lysine-deficient, wheat-based diets on growth performance of weaner pigs. Aust J Agric Res, 2003, 54: 323~330.
    178 Selle, P.H., Ravindran, V. Microbial phytase in poultry nutrition. Animal Feed Science and Technology, 2007, 135: 1~41.
    179 Shimizu, M. Purification and characterization of phytases from Bacillus subtilis (natto) N-77. Biosci Biotechnol Biochem, 1992, 56: 1266~1269.
    180 Shin, S., Ha, N.C., Oh, B.C., Oh, T.K., and Oh, B.H. 2001. Enzyme mechanism and catalytic property of beta propeller phytase. Structure, 9: 851~858.
    181 Silversides, F., Scott, T., Bedford, M. The effect of phytase enzyme andlevel on nutrient extraction by broilers. Poult Sci, 2004, 83: 985~989.
    182 Simon, O., Igbasan, F. In vitro properties of phytases from various microbial origins. Int J Food Sci Technol, 2002, 37: 813~822.
    183 Siren, M. New myo-inositol triphosphoric acid isomer. Pat. SW 052950. 1986a.
    184 Siren, M. Stabilized pharmaceutical and biological material composition. Pat. SE 003165. 1986b.
    185 Stahl, C.H., Wilson, D.B., Lei, X.G. Comparison of extracellular Escherichia coli AppA phytases expressed in Streptomyces lividans and Pichia pastoris. Biotechnol Lett, 2003, 25: 827~831.
    186 Suzuki, U., Yoshimurs, K., Takaishi, M. Ueber ein Enzym―Phytase‖das―Anhydro-oxy-methylen diphosphorsaure‖Spaltet Tokyo Imper Univ Coll Agric Bull, 1907, 7: 503~512.
    187 Sweeten, J.M. Livetock and poultry waste management: a national overview. In: Blake, J.D., Magette, W., editors. National Livestock, Poultry and Aquaculture Waste Management. St. Joseph,Minnesota: Amer Soc Agric Eng, 1992, pp. 4~15. .
    188 Tambe, S.M., Kaklij, G.S., Kelkar, S.M., Parekh, L.J. Two distinct molecular forms of phytase from Klebsiella aerogenes: Evidence for unusually small active enzyme peptide. J Ferment Bioeng, 1994, 77: 23~27.
    189 Tomschy, A., Brugger, R., Lehmann, M., Svendsen, A., Vogel, K., Kostrewa, D., Lassen, S.F., Burger, D., Kronenberger, A., van Loon, A.P., et al. Engineering of phytase for improved activity at low pH. Appl Environ Microbiol, 2002, 68: 1907~1913.
    190 Tomschy, A., Tessier, M., Wyss, M., Brugger, R., Broger, C., Schnoebelen, L., van Loon, A.P., Pasamontes, L. Optimization of the catalytic properties of Aspergillus fumigatus phytase based on the three-dimensional structure. Protein Sci, 2000a, 9: 1304~1311.
    191 Tomschy, A., Wyss, M., Kostrewa, D., Vogel, K., Tessier, M., Hofer, S., Burgin, H., Kronenberger, A., Remy, R., van Loon, A.P., et al. Active site residue 297 of Aspergillus niger phytase critically affects the catalytic properties. FEBS Lett, 2000b, 472: 169~172.
    192 Tye, A.J., Siu, F.K., Leung, T.Y., Lim, B.L. Molecular cloning and the biochemical characterization of two novel phytases from B. subtilis 168 and B. licheniformis. Appl Microbiol Biotechnol, 2002, 59: 190~197.
    193 Ullah, A.H. Aspergillus ficuum phytase: partial primary structure, substrate selectivity, and kinetic characterization. Prep Biochem, 1988, 18: 459~471.
    194 Ullah, A.H., Cummins, B.J. Purification, N-terminal amino acid sequence and characterization of pH 2.5 optimum acid phosphatase (E.C. 3.1.3.2) from Aspergillus ficuum. Prep Biochem, 1987, 17: 397~422.
    195 Ullah, A.H., Cummins, B.J. Aspergillus ficuum extracellular pH 6.0 optimum acid phosphatase: purification, N-terminal amino acid sequence, and biochemical characterization. Prep Biochem, 1988, 18: 37~65.
    196 Ullah, A.H., Cummins, B.J., Dischinger, H.C., Jr. Cyclohexanedione modification of arginine at the active site of Aspergillus ficuum phytase. Biochem Biophys Res Commun, 1991, 178: 45~53.
    197 Urbano, G., Lopez-Jurado, M., Aranda, P., Vidal-Valverde, C., Tenorio, E., Porres, J. The role of phytic acid in legumes: antinutrient or beneficial function? J Physiol Biochem, 2000, 56: 283~294.
    198 Usmani, N., Jafri, A.K. Influence of dietary phytic acid on the growth, conversion efficiency, and carcass composition of mrigal Cirrhinus mrigala (Hamilton) fry. J World Aqua Soc, 2003, 33: 199~204.
    199 Van Etten, R.L. Human prostatic acid phosphatase: a histidine phosphatase. Ann N Y Acad Sci, 1982, 390: 27~51.
    200 Van Etten, R.L., Davidson, R., Stevis, P.E., MacArthur, H., Moore, D.L. Covalent structure, disulfide bonding, and identification of reactive surface and active site residues of human prostatic acid phosphatase. J Biol Chem, 1991, 266: 2313~2319.
    201 van Hartingsveldt, W., van Zeijl, C.M., Harteveld, G.M., Gouka, R.J., Suykerbuyk, M.E., Luiten, R.G., van Paridon, P.A., Selten, G.C., Veenstra, A.E., van Gorcom, R.F., et al. Cloning,characterization and overexpression of the phytase-encoding gene (phyA) of Aspergillus niger. Gene, 1993, 127: 87~94.
    202 Vats, P., Banerjee, U.C. Biochemical characterisation of extracellular phytase (myo-inositol hexakisphosphate phosphohydrolase) from a hyper-producing strain of Aspergillus niger van Teighem. J Ind Microbiol Biotechnol, 2005, 32: 141~147.
    203 Verwoerd, T.C., van Paridon, P.A., van Ooyen, A.J., van Lent, J.W., Hoekema, A., Pen, J. Stable accumulation of Aspergillus niger phytase in transgenic tobacco leaves. Plant Physiol, 1995, 109: 1199~1205.
    204 Vincent, J.B., Crowder, M.W., Averill, B.A. Hydrolysis of phosphate monoesters: a biological problem with multiple chemical solutions. Trends Biochem Sci, 1992, 17: 105~110.
    205 Viveros, A., Brenes, A., Arija, I., Centeno, C. Effects of microbial phytases supplementation on mineral utilization and serum enzyme activities in broiler chicks fed different levels of phosphorus. Poult Sci, 2002, 81: 1172~1183.
    206 Vohra, A., Satyanarayana, T. Phytase production by the yeast, Pichia anomala. Biotechnol Lett, 2001, 23: 551~554.
    207 Vohra, A., Satyanarayana, T. Purification and characterization of a thermostable and acid-stable phytase from Pichia anomala. World J Microbiol Biotechnol, 2002, 18: 687~691.
    208 Vohra, A., Satyanarayana, T. Phytases: microbial sources, production, purification, and potential biotechnological applications. Crit Rev Biotechnol, 2003, 23: 29~60.
    209 Wang, Y., Gao, X., Su, Q., Wu, W., An, L. Expression of a heat stable phytase from Aspergillus fumigatus in tobacco (Nicotiana tabacum L. cv. NC89). Indian J Biochem Biophys, 2007, 44: 26~30.
    210 Wang, Y., Yao, B., Zeng, H., Shi, X., Cao, S., Yuan, T., Fan, Y. Purification and property of neutral phytase form Bacillus subtilis. Weishengwu Xuebao, 2001, 41: 198~203.
    211 Weaver, J.D., Mullaney, E.J., Lei, X.G. Altering the substrate specificity site of Aspergillus niger PhyB shifts the pH optimum to pH 3.2. Appl Microbiol Biotechnol, 2007, 76: 117~122.
    212 Williams, S.G. The Role of Phytic Acid in the Wheat Grain. Plant Physiol, 1970, 45: 376~381.
    213 Wodzinski, R.J., Ullah, A.H. Phytase. Adv Appl Microbiol, 1996, 42: 263~302.
    214 Wyss, M., Brugger, R., Kronenberger, A., Remy, R., Fimbel, R., Oesterhelt, G., Lehmann, M., van Loon, A.P. Biochemical characterization of fungal phytases (myo-inositol hexakisphosphate phosphohydrolases): catalytic properties. Appl Environ Microbiol, 1999a, 65: 367~373.
    215 Wyss, M., Pasamontes, L., Friedlein, A., Remy, R., Tessier, M., Kronenberger, A., Middendorf, A., Lehmann, M., Schnoebelen, L., Rothlisberger, U., et al. Biophysical characterization of fungal phytases (myo-inositol hexakisphosphate phosphohydrolases): molecular size, glycosylation pattern, and engineering of proteolytic resistance. Appl Environ Microbiol 1999b, 65: 359~366.
    216 Xiang, T., Liu, Q., Deacon, A.M., Koshy, M., Kriksunov, I.A., Lei, X.G., Hao, Q., Thiel, D.J. Crystal structure of a heat-resilient phytase from Aspergillus fumigatus, carrying a phosphorylated histidine. J Mol Biol, 2004, 339: 437~445.
    217 Xiao, K., Harrison, M.J., Wang, Z.Y. Transgenic expression of a novel M. truncatula phytase gene results in improved acquisition of organic phosphorus by Arabidopsis. Planta, 2005, 222: 27~36.
    218 Yanke, L.J., Selinger, L.B., Cheng, K.J. Phytase activity of Selenomonas ruminantium: a preliminary characterization. Lett Appl Microbiol, 1999, 29: 20~25.
    219 Zamyatnin, A.A. Protein volume in solution. Prog Biophys Mol Biol, 1972, 24: 107~123.
    220 Zhang, W., Lei, X.G. Cumulative improvements of thermostability and pH-activity profile of Aspergillus niger PhyA phytase by site-directed mutagenesis. Appl Microbiol Biotechnol, 2008, 77: 1033~1040.
    221 Zimmermann, P., Zardi, G., Lehmann, M., Zeder, C., Amrhein, N., Frossard, E., Bucher, M. Engineering the root-soil interface via targeted expression of a synthetic phytase gene in trichoblasts. Plant Biotechnol J, 2003, 1: 353~360.
    222 Zoller, M.J., Smith, M. Oligonucleotide-directed mutagenesis using M13-derived vectors: an efficient and general procedure for the production of point mutations in any fragment of DNA. Nucleic Acids Res, 1982, 10: 6487~6500.
    223 Zyla, K., Mika, M., Stodolak, B., Wikiera, A., Koreleski, J., Swiatkiewicz, S. Towards complete dephosphorylation and total conversion of phytates in poultry feeds. Poult Sci, 2004, 83: 1175~1186.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700