计算机辅助设计提高宇佐美曲霉GHF11木聚糖酶热稳定性的研究
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摘要
β-1,4-内切木聚糖酶(EC3.2.1.8)是一类从木聚糖主链的内部随机切割β-1,4木糖苷键的水解酶,简称木聚糖酶。近年来,随着人们对自然界半纤维素资源的开发和低聚木糖生理功能的发现,木聚糖酶获得了广泛的应用。宇佐美曲霉(Aspergillus usamii) E001可产具高催化活性的中温木聚糖酶,为了进一步提高木聚糖酶的活力,并探讨其耐热机制,本论文克隆和表达了来自A. usamii E001的糖苷水解酶11家族(GHF11)木聚糖酶AusXyn11D及AusXyn11A的基因序列。并以具高比酶活的AusXyn11A为研究对象,通过分子动力学模拟的方法指导其N端替换,以改善其热稳定性,此外,还分析了杂合木聚糖酶的耐热机制及水解产物特性。
     以曲霉基因组中的木聚糖酶保守序列为基础,利用多种PCR技术获得A. usamiiE001木聚糖酶基因Ausxyn11D的完整cDNA和DNA序列,其GenBank登录号分别为JQ219105和HQ724287。氨基酸序列同源性分析结果表明AusXyn11D具有GHF11木聚糖酶高度保守的氨基酸片段及催化活性中心,且与A. usamii E001中两种已知的GHF11木聚糖酶的同源性分别为58%和37%。同源建模结果显示,AusXyn11D具有GHF11木聚糖酶典型的“右手”型结构,表明AusXyn11D属于GHF11木聚糖酶。
     依据Ausxyn11D的cDNA序列设计引物,利用RT-PCR技术克隆其成熟肽基因,同时根据GenBank中A. usamii E001GHF11木聚糖酶AusXyn11A的基因序列,扩增得到成熟肽基因Ausxyn11A,然后,成功构建毕赤酵母(Pichia pastoris) GS115重组子GS115/Ausxyn11D及GS115/Ausxyn11A。经甲醇诱导表达后,重组木聚糖酶reAusXyn11D、reAusXyn11A的比酶活分别达到150.3U/mg和22,714U/mg; reAusXyn11D和reAusXyn11A的Topt分别为55℃和50℃,分别在50℃和45℃以下稳定,最适pH值均偏酸性,且pH稳定范围分别为3.5~6.5和4.0~8.0。但与reAusXyn11D相比,reAusXyn11A具有高比酶活的优点,因此具有重要的工业应用价值。此外,为了获得高产木聚糖酶的基因工程菌株,对GS115/Ausxyn11A的发酵条件进行优化,reAusXyn11A的酶活最高可达912.6U/mL,是优化前的2.14倍。
     对文献报道的耐热木聚糖酶EvXyn11TS基因序列进行毕赤酵母密码子优化,人工合成其优化基因Syxyn11,并在P. pastoris GS115中获得表达,重组木聚糖酶reSyXyn11的比酶活为363.2U/mg,Topt可高达85℃,并在80℃以下稳定,最适pH值为6.5,在pH4.5~9.0的范围内稳定,是目前最耐热的GHF11木聚糖酶之一。
     通过分子动力学模拟的方法分析AusXyn11A和EvXyn11TS的N端序列,确定用EvXyn11TS的Asn1-Arg38区域替换AusXyn11A中的Ser1-Ala33区域,以此构建杂合酶AEXynM。重组杂合木聚糖酶reAEXynM的比酶活为19,237U/mg,稍低于reAusXyn11A。reAEXynM的Topt为70℃,75℃以下稳定,较reAusXyn11A有显著性提高,其Tm值可高达91.6℃,虽略低于文献报道的EvXyn11TS的Tm值,但比reAusXyn11A提高了34.0℃,表明杂合酶的热稳定性大大提高了。
     采用分子动力学模拟的方法分析AEXynM与AusXyn11A中的差异氨基酸,并结合分子间作用力的分析,推测与AEXynM热稳定性相关的位点为Cys5、Pro9及His14,以此构建突变酶基因,获得重组突变酶reAEXynMC5T、reAEXynMP9S和reAEXynMH14N。三种突变酶的热稳定性均出现一定程度的下降,其中reAEXynMC5T的热稳定性最差,证实N端二硫键(Cys5-Cys32)的添加是AEXynM热稳定性提高的主要原因之一;而reAEXynMP9S和reAEXynMH14N则表现出相对微弱的下降,结构分析表明,Pro9可提高β-转角的刚性,而His14与Phe17可形成氢键,加固了β-折叠B1与B2之间的连接,是影响AEXynM热稳定性的重要因素。
     以玉米芯木聚糖及桦木木聚糖为底物,研究AEXynM的水解过程及产物,研究结果显示玉米芯木聚糖的水解产物以木二糖和木三糖为主,分别占水解产物总量的42.33%和38.76%;而桦木木聚糖的水解产物主要以木二糖为主,可占水解产物总量的58.56%;两种底物的水解液中仅有少量木糖被检出,表明其在低聚木糖制备方面具有极大的应用潜力。
Xylanase (EC3.2.1.8), abbreviated from β-1,4-endoxylanase, can catalyze the hydrolysisof internal β-1,4-D-xylosidic linkages of xylans. Recently, with the development ofhemicellulose and xylooligosaccharides, xylanases have been applied in many industryprocesses. Aspergillus usamii E001can produce a series of mesophilic xylanases with highspecific activities. To further improve the activity of xylanase, and study its thermotolerantmechanism, we cloned and expressed two genes encoding glycoside hydrolase family11(GHF11) xylanases from A. usamii E001(AusXyn11D and AusXyn11A), respectively. Then,to improve the thermostability of AusXyn11A, its N-terminus replacement was predicted bycomputer aided design using molecular dynamics (MD) simulation. In addtion, thethermotolerant mechanism and hydrolytic product of the hybrid xylanase were analyzed.
     Based on the conserved peptide segments in four putative xylanase sequences fromAspergillus sp., the full-length cDNA of Ausxyn11D, a gene that encodes a xylanase of A.usamii E001, was obtained, and then its DNA sequence was amplified by PCR. The cDNAand DNA sequences were deposited in the GenBank database under accession no. JQ219105and HQ724287, respectively. Multiple homology alignment of amino acid sequences verifiedthat AusXyn11D contained the motifs and catalytic residues that were strictly conservedamong all GHF11xylanases. The similarities of the primary structure of AusXyn11D withtwo GHF11xylanases from A. usamii E001were58and37%, respectively. Homologymodeling revealed that the3-D structure of AusXyn11D conformed to the GHF11xylanaseoverall crystal one, resembling the shape of a partially closed right hand. All these featuresverified that AusXyn11D was a member of GHF11.
     According to the cDNA sequence of Ausxyn11D, its mature peptide-encoding gene wasamplified by RT-PCR. At the same time, a gene (Ausxyn11A) coding for the mature peptide ofAusXyn11A was also cloned based on the information of its cDNA sequence in GenBank.After that, Pichia pastoris GS115transformants (GS115/Ausxyn11D and GS115/Ausxyn11A)were successfully constructed. After induction by menthanol, the specific activities ofrecombinant xylanases (reAusXyn11D and reAusXyn11A) were150.3and22,714U/mg,respectively. The reAusXyn11D and reAusXyn11A displayed their highest activities at55and50℃, and they were stable at50and45℃, respectively. Their pH optima were acidic, and thereAusXyn11D was stable at a pH range of3.5-6.5, while reAusXyn11A displayed pH stabilityat a broad range of4.0-8.0. The specific activity of reAusXyn11A was much higher than thatof reAusXyn11D, which would make reAusXyn11A a good candidate for industrialapplication. Furthermore, the expression conditions of GS115/Ausxyn11A were optimized. Asa result, the activity of reAusXyn11A reached912.6U/mL which was2.14times as high asthat expressed using the standard protocol.
     A codon-optimized gene, Syxyn11, which encodes a thermostable xylanase (EvXyn11TS)was synthesized and expressed in P. pastoris GS115. The specific activity of reSyXyn11was363.2U/mg. The reSyXyn11displayed pH optimum at6.5and pH stability at a broad rangeof4.5-9.0. Its temperature optimum and stability were85and80℃, respectively. The reSyXyn11was one of the most thermostable GHF11xylanases.
     A hybrid xylanase (AEXynM) was predicted by MD simulation, and constructed bysubstituting the N-terminal33amino acids of AusXyn11A with the corresponding38ones ofEvXyn11TS. As a result, the specific activity of reAEXynM was19,237U/mg, slightly lowerthan that of reAusXyn11A. The temperature optimum and stability of reAEXynM reached70and75℃, respectively, much higher than those of reAusXyn11A. The melting temperature(Tm) of reAEXynM was slightly lower than that of EvXyn11TS, but increased by34.0℃ascompared with that of reAusXyn11A. All the results verified that the thermostability ofAusXyn11A was obviously enhanced by N-terminus replacement.
     Based on MD simulation and intramolecular interaction analysis, three amino acids(Cys5, Pro9and His14) in the replaced N-terminus were considered to be responsible for thehigh thermostability of AEXynM. As a result, three recombinant mutants derived fromAEXynM (reAEXynMC5T, reAEXynMP9Sand reAEXynMH14N) were obtained by site-directedmutagenesis, respectively. The thermostabilities of three mutants decreased obviouslycompared with that of reAEXynM. Among that, the mutation of C5T caused the mostsignificant decrease in thermostability which confirmed that a unique disulfide bridge(Cys5-Cys32) may confer the high thermostability on AEXynM. Besides that, the Pro9inβ-turn and a hydrogen bond between His14and Phe17could be important to the thermostabilityof AEXynM.
     The hydrolytic time-course of AEXynM verified that the hydrolysis velocity of corncobsxylan was much slower than that of birchwood xylan. Xylobiose and xylotriose as the majorhydrolytic products were excised from corncob xylan by AEXynM, and their contentsreached42.33and38.76%, respectively. However, xylobiose as the major hydrolytic productwas released from birchwood xylan by AEXynM with content of58.56%. A trace of xylosewas detected during the hydrolysis, suggesting that AEXynM would be suitable for theproduction of xylooligosaccharides.
引文
1.谢响明,孙晓霞,吴玉英等.绿色糖单孢菌产木聚糖酶规律及其耐碱耐热性的初步研究[J].生命科学研究,2005,9(1):55-59.
    2. Yamaura I, Matsumoto T, Funatsu M, et al. Purification and some properties of endo-1,3-β-D-xylanasefrom Pseudomonas sp. PT-5[J]. Agric Biol Chem1990,54(4):921-926.
    3. Kulkarni N, Shendye A, Rao M. Molecular and biotechnological aspects of xylanases [J]. FEMSMicrobiol Rev,1999,23(4):411-456.
    4. Li K, Azadi P, Collins R, et al. Relationships between activities of xylanases and xylan structures [J].Enzyme Microb Technol,2000,27(1-2):89-94.
    5. Barry V C, Dillon T. Occurrence of xylans in marine algae [J]. Nature,1940,146(620):620-620.
    6. Nunn J R, Parolis H, Russell I. Polysaccharides of the red alga Chaetangium erinaceum: Part I.isolation and characterisation of the water-soluble xylan [J]. Carbohyd Res,1973,26(1):169-180.
    7. Sunna A, Antranikian G. Xylanolytic enzymes from fungi and bacteria [J]. Crit Rev Biotechnol,1997,17(1):39-67.
    8. Dekker R F H. Biodegradation of the hetero-1,4-linked xylans [C]. In: Lewis NG, Paice M G, eds.Plant cell wall polymers, American Chemical Society Symposium Series. Washington: AmericanChemical Society,1989.619-629.
    9. Puls J, Schuseil J. Chemistry of hemicelluloses: relationship between hemicellulose structure andenzymes required for hydrolysis [C]. In: Coughlan M P, Hazlewood G P, eds. Hemicellulose andHemicellulases. London: Portland Press,1993.1-28.
    10. Khandeparker R, Numan M T. Bifunctional xylanases and their potential use in biotechnology [J]. JInd Microbiol Biotechnol,2008,35(7):635-644.
    11. Biely P, Vrsanska M, Tenkanen M, et al. Endo-β-1,4-xylanase families: differences in catalyticproperties [J]. J Biotechnol,1997,57(1-3):151-166.
    12. Durand R, Rascle C, Fèvre M. Molecular characterization of xyn3, a member of the endoxylanasemultigene family of the rumen anaerobic fungus Neocallimastix frontalis [J]. Curr Genet,1996,30(6):531-540.
    13. Zhang J X, Flint H J. A bifunctional xylanase encoded by the xynA gene of the rumen cellulolyticbacterium Ruminococcus flavefaciens17comprises two dissimilar domains linked by anasparagine/glutamine-rich sequence [J]. Mol Microbiol,1992,6(8):1013-1023.
    14. White A, Withers S G, Gilkes N R, et al. Crystal structure of the catalytic domain of theβ-1,4-glycanase Cex from Cellulomonas fimi [J]. Biochemistry,1994,33(42):12546-12552.
    15. Zhu H, Paradis F W, Krell P J, et al. Enzymatic specificities and modes of action of the two catalyticdomains of the Xync xylanase from Fibrobacter succinogenes S85[J]. J Bacteriol,1994,176(13):3885-3894.
    16.杨浩萌,姚斌,范云六.木聚糖酶分子结构与重要酶学性质关系的研究进展[J].生物工程学报,2005,21(1):6-11.
    17. Nakamura M, Nagamine T, Takenaka A, et al. Molecular cloning, nucleotide sequence andcharacteristics of a xylanase gene (xynA) from Ruminococcus albus7[J]. Anim Sci J,2002,73(5):347-352.
    18. Morris D D, Gibbs M D, Chin C W J, et al. Cloning of the xynB gene from Dictyoglomusthermophilum Rt46B.1and action of the gene product on kraft pulp [J]. Appl Environ Microbiol,1998,64(5):1759-1765.
    19. Black G W, Hazlewood G P, Millward-Sadler S J, et al. A modular xylanase containing a novelnoncatalytic xylan-specific binding domain [J]. Biochem J,1995,307:191-195.
    20. McIntosh L P, Hand G, Johnson P E, et al. The pKaof the general acid/base carboxyl group of aglycosidase cycles during catalysis: A13C-NMR study of Bacillus circuluns xylanase [J]. Biochemistry,1996,35(31):9958-9966.
    21. Visser J, Beldman G, van Someren M A K, et al. Xylans and xylanases [M]. Amsterdam: Elsevier,
    1992.
    22. Campbell R L, Rose D R, Wakarchuk W W, et al. A comparison of the structure of the20kDxylanases from Trichoderma harzianum and Bacillus circulans [C]. In: Suominen P, Reinikainen T,eds. Trichoderma reesei cellulases and other hydrolases, Proceedings of the Tricel93Symposium.Helsinki: Foundation for Biotechnological and Industrial Fermentation Research,1993.63-77.
    23. Harris G W, Pickersgill R W, Connerton I, et al. Structural basis of the properties of an industriallyrelevant thermophilic xylanase [J]. Proteins,1997,29(1):77-86.
    24. Jeffries T W. Biochemistry and genetics of microbial xylanases [J]. Curr Opin Biotech,1996,7(3):337-342.
    25. Sapag A, Wouters J, Lambert C, et al. The endoxylanases from family11: computer analysis of proteinsequences reveals important structural and phylogenetic relationships [J]. J Biotechnol,2002,95(2):109-131.
    26. Pa s G, Berrin J G, Beaugrand J. GH11xylanases: Structure/function/properties relationships andapplications [J]. Biotechnol Adv,2012,30(3):564-592.
    27. Ito K, Iwashita K, Iwano K. Cloning and sequencing of the xynC gene encoding acid xylanase ofAspergillus kawachii [J]. Biosci Biotech Biochem,1992,56(8):1338-1340.
    28. Nakamura S, Wakabayashi K, Nakai R, et al. Production of alkaline xylanase by a newly isolatedalkaliphilic Bacillus sp. strain41M-1[J]. World J Microbiol Biotechnol,1993,9(2):221-224.
    29. T rr nen A, Rouvinen J. Structural comparison of two major endo-1,4-xylanases from Trichodermareesei [J]. Biochemistry,1995,34(3):847-856.
    30. Hakulinen N, Turunen O, J nis J, et al. Three-dimensional structures of thermophilic β-1,4-xylanasesfrom Chaetomium thermophilum and Nonomuraea flexuosa: Comparison of twelve xylanases inrelation to their thermal stability [J]. Eur J Biochem,2003,270(7):1399-1412.
    31. Pa s G, O’Donohue M J. Engineering increased thermostability in the thermostable GH-11xylanasefrom Thermobacillus xylanilyticus [J]. J Biotechnol,2006,125(3):338-350.
    32. Dumon C, Varvak A, Wall M A, et al. Engineering hyperthermostability into a GH11xylanase ismediated by subtle changes to protein structure [J]. J Biol Chem,2008,283(33):22557-22564.
    33. Shin J H, Choi J H, Lee O S, et al. Thermostable xylanase from Streptomyces thermocyaneoviolaceusfor optimal production of xylooligosaccharides [J]. Biotechnol Bioproc E,2009,14(4):391-399.
    34. Helianti I, Nurhayati N, Wahyuntari B. Cloning, sequencing, and expression of a β-1,4-endoxylanasegene from Indonesian Bacillus licheniformis strain I5in Escherichia coli [J]. World J MicrobiolBiotechnol,2008,24(8):1273-1279.
    35. Zhou C, Bai H, Deng S, et al. Cloning of a xylanase gene from Aspergillus usamii and its expressionin Escherichia coli [J]. Bioresour Technol,2008,99(4):831-838.
    36. Parachin N S, Siqueira S, de Faria F P, et al. Xylanases from Cryptococcus flavus isolate I-11:Enzymatic profile, isolation and heterologous expression of CfXYN1in Saccharomyces cerevisiae [J].J Mol Catal B-Enzym,2009,59(1-3):52-57.
    37. Furniss C S M, Williamson G, Kroon P A. The substrate specificity and susceptibility to wheatinhibitor proteins of Penicillium funiculosum xylanases from a commercial enzyme preparation [J]. JSci Food Agric,2005,85(4):574-582.
    38. Devillard E, Newbold C J, Scott K P, et al. A xylanase produced by the rumen anaerobic protozoanPolyplastron multivesiculatum shows close sequence similarity to family11xylanases fromGram-positive bacteria [J]. FEMS Microbiol Lett,1999,181(1):145-152.
    39. Beli n T, Van Campenhout S, Van Acker M, et al. Cloning and characterization of two endoxylanasesfrom the cereal phytopathogen Fusarium graminearum and their inhibition profile againstendoxylanase inhibitors from wheat [J]. Biochem Bioph Res Co,2005,327(2):407-414.
    40. Daniel R M, Dines M, Petach H H. The denaturation and degradation of stable enzymes at hightemperatures [J]. Biochem J,1996,317:1-11.
    41. Collins T, Gerday C, Feller G. Xylanases, xylanase families and extremophilic xylanases [J]. FEMSMicrobiol Rev,2005,29(1):3-23.
    42.杨浩萌.来源于橄榄绿链霉菌A1的木聚糖酶XYNB的分子改良[D]:[博士学位论文].北京:中国农业科学院,2006.
    43. He J, Yu B, Zhang K, et al. Thermostable carbohydrate binding module increases the thermostabilityand substrate-binding capacity of Trichoderma reesei xylanase2[J]. New Biotechnol,2009,26(1-2):53-59.
    44. Wang Q, Xia T. Importance of C-terminal region for thermostability of GH11xylanase fromStreptomyces lividans [J]. Appl Biochem Biotechnol,2008,144(3):273-282.
    45. Matsumura M, Signor G, Matthews B W. Substantial increase of protein stability by multipledisulphide bonds [J]. Nature,1989,342(6247):291-293.
    46. Gruber K, Klintschar G, Hayn M, et al. Thermophilic xylanase from Thermomyces lanuginosus:High-resolution X-ray structure and modeling studies [J]. Biochemistry,1998,37(39):13475-13485.
    47. Michaux C, Pouyez J, Mayard A, et al. Structural insights into the acidophilic pH adaptation of a novelendo-1,4-β-xylanase from Scytalidium acidophilum [J]. Biochimie,2010,92(10):1407-1415.
    48. Turunen O, Etuaho K, Fenel F, et al. A combination of weakly stabilizing mutations with a disulfidebridge in the α-helix region of Trichoderma reesei endo-1,4-β-xylanase II increases the thermalstability through synergism [J]. J Biotechnol,2001,88(1):37-46.
    49. Xue H, Zhou J, You C, et al. Amino acid substitutions in the N-terminus, cord and α-helix domainsimproved the thermostability of a family11xylanase XynR8[J]. Ind Microbiol Biotechnol,2012,39(9):1279-1288.
    50.丁彦蕊,蔡宇杰,须文波.氢键与蛋白质耐热性关系的研究[J].计算机与应用化学,2007,24(5):641-644.
    51. Purmonen M, Valjakka J, Takkinen K, et al. Molecular dynamics studies on the thermostability offamily11xylanases [J]. Protein Eng Des Sel,2007,20(11):551-559.
    52. You C, Yuan H, Huang Q, et al. Substrate molecule enhances the thermostability of a mutant of afamily11xylanase from Neocallimastix patriciarum [J]. Afr J Biotechnol,2010,9(9):1288-1294.
    53.陈路清,张秀艳,唐彦捷等.嗜热酶的稳定机制和稳定策略的研究进展[J].科技通报,2008,24(6):792-798.
    54. Kim T, Joo J C, Yoo Y J. Hydrophobic interaction network analysis for thermostabilization of amesophilic xylanase [J]. J Biotechnol,2012,161(1):49-59.
    55. You C, Huang Q, Xue H, et al. Potential hydrophobic interaction between two cysteines in interiorhydrophobic region improves thermostability of a family11xylanase from NeocallimastixPatriciarum [J]. Biotechnol Bioeng,2010,105(5):861-870.
    56. Haney P J, Badger J H, Buldak G L, et al. Thermal adaptation analyzed by comparison of proteinsequences from mesophilic and extremely thermophilic Methanococcus species [J]. Proc. Natl. Acad.Sci. USA,1999,96(7):3578-3583.
    57. Korkegian A, Black M E, Baker D, et al. Computational thermostabilization of an enzyme [J]. Science,2005,308(5723):857-860.
    58.杨浩萌,王亚茹,伍宁丰等. N13D、S40E点突变提高木聚糖酶XYNB的热稳定性[J].微生物学通报,2007,34(3):533-536.
    59. Georis J, de Lemos Esteves F, Lamotte-Brasseur J, et al. An additional aromatic interaction improvesthe thermostability and thermophilicity of a mesophilic family11xylanase: Structural basis andmolecular study [J]. Protein Sci,2000,9(3):466-475.
    60. Sriprang R, Asano K, Gobsuk J, et al. Improvement of thermostability of fungal xylanase by usingsite-directed mutagenesis [J]. J Biotechnol,2006,126(4):454-462.
    61. Watanabe K, Hata Y, Kizaki H, et al. The refined crystal structure of Bacillus cereusoligo-1,6-glucosidase at2.0resolution: Structural characterization of proline-substitution sites forprotein thermostabilization [J]. J Mol Biol,1997,269(1):142-153.
    62. Ebanks R, Dupont M, Shareck F, et al. Development of an Escherichia coli expression system andthermostability screening assay for libraries of mutant xylanase [J]. J Ind Microbiol Biotechnol,2000,25(6):310-314.
    63. Taibi Z, Saoudi B, Boudelaa M, et al. Purification and biochemical characterization of a highlythermostable xylanase from Actinomadura sp. strain Cpt20isolated from poultry compost [J]. ApplBiochem Biotechnol,2012,166(3):663-679.
    64. Trevizano L M, Ventorim R Z, de Rezende S T, et al. Thermostability improvement of Orpinomyces sp.xylanase by directed evolution [J]. J Mol Catal B-Enzym,2012,81:12-18.
    65. Miyazaki K, Takenouchi M, Kondo H, et al. Thermal stabilization of Bacillus subtilis family-11xylanase by directed evolution [J]. J Biol Chem,2006,281(15):10236-10242.
    66.李清峰,马向东,彭虹旎等.木聚糖酶耐热性研究进展[J].中国畜牧杂志,2009,45(11):57-59.
    67.闵柔.二硫键和拇指结构对木聚糖酶温度及pH特性的影响[D]:[硕士学位论文].无锡:江南大学,2013.
    68. Sun J Y, Liu M Q, Xu Y L, et al. Improvement of the thermostability and catalytic activity of amesophilic family11xylanase by N-terminus replacement [J]. Protein Expres Purif,2005,42(1):122-130.
    69.陈颖健.生物信息学:融合生物科学与计算机科技的新学科[J].求是,2003,7:53-54.
    70.孔祥禄.计算机辅助酶耐热性研究及分子设计[D]:[硕士学位论文].广州:华南理工大学,2010.
    71.刘亮伟.木聚糖酶蛋白质序列分析、分子进化和分子模拟[D]:[博士学位论文].无锡:江南大学,
    2005.
    72. Joo J C, Pohkrel S, Pack S P, et al. Thermostabilization of Bacillus circulans xylanase viacomputational design of a flexible surface cavity [J]. J Biotechnol,2010,146(1-2):31-39.
    73. McCammon J A, Gelin B R, Karplus M. Dynamics of folded proteins [J]. Nature,1977,267(5612):585-590.
    74. Joo J C, Pack S P, Kim Y H, et al. Thermostabilization of Bacillus circulans xylanase: Computationaloptimization of unstable residues based on thermal fluctuation analysis [J]. J Biotechnol,2011,151(1):56-65.
    75.赵友杰,曹永忠,张剑峰等.生物信息学中的数据库技术[J].生物信息学,2007,5(3):137-139.
    76. Cobos A, Estrada P. Effect of polyhydroxylic cosolvents on the thermostability and activity ofxylanase from Trichoderma reesei QM9414[J]. Enzyme Microb Tech,2003,33(6):810-818.
    77. Verjans P, Dornez E, Delcour J A, et al. Selectivity for water-unextractable arabinoxylan and inhibitionsensitivity govern the strong bread improving potential of an acidophilic GH11Aureobasidiumpullulans xylanase [J]. Food Chem,2010,123(2):331-337.
    78.陆健,曹钰,陈坚等.耐酸性木聚糖酶在清酒酿造中的作用[J].食品与发酵工业,2002,28(1):27-30.
    79. Biely P. Microbial xylanolytic systems [J]. Trends Biotechnol,1985,3(11):286-290.
    80. Wong K K Y, Tan L U L, Saddler J N. Multiplicity of β-1,4-xylanase in microorganisms: functions andapplications [J]. Microbiol rev,1988,52(3):305-317.
    81.许正宏,熊筱晶,陶文沂.低聚木糖的生产及应用研究进展[J].食品与发酵工业,2002,28(1):56-59.
    82. Akpinar O, Erdogan K, Bostanci S. Production of xylooligosaccharides by controlled acid hydrolysisof lignocellulosic materials [J]. Carbohyd Res,2009,344(5):660-666.
    83. Chen C C, Adolphson R, Dean J F D, et al. Release of lignin from kraft pulp by a hyperthermophilicxylanase from Thermatoga maritima [J]. Enzyme Microb Tech,1997,20(1):39-45.
    84.刘明启.提高木聚糖酶热稳定性、催化活性和结合水解纤维素能力的研究[D]:[博士学位论文].杭州:浙江大学,2007.
    85. Katahira S, Fujita Y, Mizuike A, et al. Construction of a xylan-fermenting yeast strain throughcodisplay of xylanolytic enzymes on the surface of xylose-utilizing Saccharomyces cerevisiae cells [J].Appl Environ Microb,2004,70(9):5407-5414.
    86.江正强.微生物木聚糖酶的生产及其在食品工业中应用的研究进展[J].中国食品学报,2005,5(1):1-9.
    87. Polizeli M L T M, Rizzatti A C S, Monti R, et al. Xylanases from fungi: properties and industrialapplications [J]. Appl Microbiol Biotechnol,2005,67(5):577-591.
    88.万红贵,武振军,蔡恒等.微生物发酵产木聚糖酶研究进展[J].中国生物工程杂志,2010,30(2):141-146.
    89.曾宇成,张树政.海枣曲霉木聚糖酶的提纯和性质[J].微生物学报,1987,27(4):343-349.
    90.符丹丹,谢慧,邬敏辰.宇佐美曲霉产木聚糖酶的固态发酵条件研究[J].食品与发酵工业,2005,31(4):50-53.
    91.周晨妍.宇佐美曲霉木聚糖酶基因的克隆、表达及定向诱变研究[D]:[博士学位论文].无锡:江南大学,2008.
    92. Chantasingh D, Pootanakit K, Champreda V, et al. Cloning, expression, and characterization of axylanase10from Aspergillus terreus (BCC129) in Pichia pastoris [J]. Protein Expres Purif,2006,46(1):143-149.
    93. Luo H, Wang Y, Li J, et al. Cloning, expression and characterization of a novel acidic xylanase,XYL11B, from the acidophilic fungus Bispora sp MEY-1[J]. Enzyme Microb Tech,2009,45(2):126-133.
    94. Tenkanen M, Puls J, Poutanen K. Two major xylanases of Trichoderma reesei [J]. Enzyme MicrobTech,1992,14(7):566-574.
    95.杨瑞鹏,胡慰望,赵学慧.黑曲霉A34菌株的木聚糖酶分离纯化及其性质研究[J].华中农业大学学报,1991,10(1):117-123.
    96. Pel H J, de Winde J H, Archer D B, et al. Genome sequencing and analysis of the versatile cell factoryAspergillus niger CBS513.88[J]. Nat Biotechnol,2007,25(2):221-231.
    97.邵佩兰,徐明,朱晓红.影响玉米芯木聚糖提取的因素探讨[J].宁夏农学院学报,2002,23(2):56-57.
    98.黄伟达,王奕然,钱志康等.利用PCR确定已知DNA序列的两侧未知序列的方法[P].中国专利,1418968A.2003-05-21.
    99. Bradford M M. A rapid and sensitive method for the quantitation of microgram quantities of proteinutilizing the principle of protein-dye binding [J]. Anal Biochem,1976,72:248-254.
    100. Bailey M J, Biely P, Poutanen K. Interlaboratory testing of methods for assay of xylanase activity [J]. JBiotechnol,1992,23(3):257-270.
    101.杨月梅,江贤章,张娟梅等.扩展青霉碱性脂肪酶基因5’端侧翼区域的克隆与鉴定[J].工业微生物,2007,37(1):14-19.
    102.马志杰,魏雅萍,钟金城等.藏绵羊GHR基因5′侧翼区序列特征分析[J].遗传,2007,29(8):963-971.
    103. Schaufler L E, Klevit R E. Mechanism of DNA binding by the ADR1zinc finger transcription factoras determined by SPR [J]. J Mol Biol,2003,329(5):931-939.
    104.周颖君,杨亦桦,武淑文等.棉铃虫细胞色素P450CYP9A12基因5′-上游区的克隆及序列分析[J].昆虫学报,2008,51(2):120-125.
    105.郑茂恩,潘登科,冯书堂等.小型猪生长激素基因启动子区SNPs分析[J].畜牧兽医学报,2009,40(5):639-644.
    106. Mott B H, Bassman J, Pikaart M J. A molecular dissection of the interaction between the transcriptionfactor Gata-1zinc finger and DNA [J]. Biochem Bioph Res Co,2004,316(3):910-917.
    107. Cereghino J L, Cregg J M. Heterologous protein expression in the methylotrophic yeast Pichiapastoris [J]. FEMS Microbiol Rev,2000,24(1):45-66.
    108. He J, Chen D, Yu B, et al. Optimization of the Trichoderma reesei endo-1,4-beta-xylanase productionby recombinant Pichia pastoris [J]. Biochem Eng J,2010,52(1):1-6.
    109. Diao Z, Ye T, Cao P, et al. Expression, purification, and characterization of recombinant humansoluble BAFF secreted from the yeast Pichia pastoris [J]. Protein Expres Purif,2007,54(1):11-17.
    110. Ujiie M, Roy C, Yaguchi M. Low-molecular-weight xylanase from Trichoderma viride [J]. ApplEnviron Microb,1991,57(6):1860-1862.
    111. Prakash P, Jayalakshmi S K, Prakash B, et al. Production of alkaliphilic, halotolerent, thermostablecellulase free xylanase by Bacillus halodurans PPKS-2using agro waste: single step purification andcharacterization [J]. World J Microbiol Biotechnol,2012,28(1):183-192.
    112.邬敏辰,符丹丹,朱劼等.宇佐美曲霉木聚糖酶的纯化和性质[J].食品与生物技术学报,2005,24(6):29-33.
    113.皮雄娥,费笛波,王龙英等.黑曲霉AS6034酸性β-甘露聚糖酶的性质研究[J].饲料研究,2006,2:50-52.
    114. Kumar S, Tsai C J, Nussinov R. Factors enhancing protein thermostability [J]. Protein Eng,2000,13(3):179-191.
    115.张红莲,姚斌,王亚茹等.链霉菌Streptomyces olivaceoviridis A1木聚糖酶基因xynA在大肠杆菌及毕赤酵母中的高效表达[J].生物工程学报,2003,19(1):41-45.
    116. Zhang M, Jiang Z, Yang S, et al. Cloning and expression of a Paecilomyces thermophila xylanase genein E. coli and characterization of the recombinant xylanase [J]. Bioresour Technol,2010,101(2):688-695.
    117. Liu M Q, Weng X Y, Sun J Y. Expression of recombinant Aspergillus niger xylanase A in Pichiapastoris and its action on xylan [J]. Protein Expres Purif,2006,48(2):292-299.
    118. Wu M, Wang J, Zhang H, et al. Cloning and sequence analysis of an acidophilic xylanase (XynI) genefrom Aspergillus usamii E001[J]. World J Microbiol Biotechnol,2011,27(4):831-839.
    119. Korona B, Korona D, Bielecki S. Efficient expression and secretion of two co-produced xylanasesfrom Aspergillus niger in Pichia pastoris directed by their native signal peptides and theSaccharomyces cerevisiae α-mating factor [J]. Enzyme Microb Tech,2006,39(4):683-689.
    120. Kinoshita K, Takano M, Koseki T, et al. Cloning of the xynNB gene encoding xylanase B fromAspergillus niger and its expression in Aspergillus kawachii [J]. J Ferment Bioeng,1995,79(5):422-428.
    121. Li J F, Gao S J, Liu X T, et al. Modified pPIC9K vector-mediated expression of a family11xylanasegene, Aoxyn11A, from Aspergillus oryzae in Pichia pastoris [J]. Ann Microbiol,2013,63(3):1109-1120
    122. Scorer C A, Clare J J, McCombie W R, et al. Rapid selection using G418of high copy numbertransformants of Pichia pastoris for high-level foreign gene expression [J]. Biotechnology,1994,12(2):181-184.
    123. Jahic M, Gustavsson M, Jansen A K, et al. Analysis and control of proteolysis of a fusion protein inPichia pastoris fed-batch processes [J]. J Biotechnol,2003,102(1):45-53.
    124. Katakura Y, Zhang W, Zhuang G, et al. Effect of methanol concentration on the production of humanβ2-glycoprotein I domain V by a recombinant Pichia pastoris: A simple system for the control ofmethanol concentration using a semiconductor gas sensor [J]. J Ferment Bioeng,1998,86(5):482-487.
    125.刘明启,孙建义,翁晓燕等.重组毕赤酵母产木聚糖酶条件的优化[J].浙江大学学报(农业与生命科学版),2006,32(2):222-226.
    126. Gaffney M, Carberry S, Doyle S, et al. Purification and characterisation of a xylanase fromThermomyces lanuginosus and its functional expression by Pichia pastoris [J]. Enzyme Microb Tech,2009,45(5):348-354.
    127. Ninawe S, Kapoor M, Kuhad R C. Purification and characterization of extracellular xylanase fromStreptomyces cyaneus SN32[J]. Bioresour Technol,2008,99(5):1252-1258.
    128.周玉恒,张厚瑞.木聚糖酶纯化的研究进展[J].现代食品科技,2006,22(1):181-185.
    129. Wang J Q, Yin X, Wu M C, et al. Expression of a family10xylanase gene from Aspergillus usamiiE001in Pichia pastoris and characterization of the recombinant enzyme [J]. J Ind MicrobiolBiotechnol,2013,40(1):75-83.
    130.邹永龙,桑月婵,彭建新等. β-l,4-内切木聚糖酶的分离纯化及其性质[J].植物学报,1999,41(11):1212-1216.
    131.孙建义.耐热木聚糖酶杂合基因的构建、表达及产物的酶学特性研究[D]:[博士学位论文].杭州:浙江大学2003.
    132. Fiser A, Do R K G, ali A. Modeling of loops in protein structures [J]. Protein Sci,2000,9(9):1753-1773.
    133. Van Der Spoel D, Lindahl E, Hess B, et al. GROMACS: Fast, flexible, and free [J]. J Comput Chem,2005,26(16):1701-1718.
    134. Berendsen H J C, van der Spoel D, van Drunen R. GROMACS: A message-passing parallel moleculardynamics implementation [J]. Comput Phys Commun,1995,91(1-3):43-56.
    135.金光泽,段作营,张莲芬等.重组融合人血清白蛋白-人白介素-2C125A突变体在毕赤酵母中的表达[J].食品与生物技术学报,2010,29(4):595-601.
    136. Irwin D, Jung E D, Wilson D B. Characterization and sequence of a Thermomonospora fusca xylanase[J]. Appl Environ Microb,1994,60(3):763-770.
    137. Schlacher A, Holzmann K, Hayn M, et al. Cloning and characterization of the gene for thethermostable xylanase XynA from Thermomyces lanuginosus [J]. J Biotechnol,1996,49(1-3):211-218.
    138. Matthews B W. Structural and genetic analysis of protein stability [J]. Annu Rev Biochem,1993,62:139-160.
    139. Jaenicke R, B hm G. The stability of proteins in extreme environments [J]. Curr Opin Struc Biol,1998,8(6):738-748.
    140.丁彦蕊,蔡宇杰,须文波.蛋白质空间结构属性与全基因组微生物耐热性的关系[J].中国生物化学与分子生物学报,2007,23(4):323-330.
    141. Reetz M T, Carballeira J D. Iterative saturation mutagenesis (ISM) for rapid directed evolution offunctional enzymes [J]. Nat Protoc,2007,2(4):891-903.
    142. Badieyan S, Bevan D R, Zhang C. Study and design of stability in GH5cellulases [J]. BiotechnolBioeng,2012,109(1):31-44.
    143. Radestock S, Gohlke H. Explotiting the link between protein rigidity and thermostability fordata-driven protein engineering [J]. Eng Life Sci,2008,8(5):507-522.
    144.田健.计算机辅助分子设计提高蛋白质热稳定性的研究[D]:[博士学位论文].北京:中国农业科学院,2011.
    145. Niesen F H, Berglund H, Vedadi M. The use of differential scanning fluorimetry to detect ligandinteractions that promote protein stability [J]. Nat Protoc,2007,2(9):2212-2221.
    146. Wang Y, Fu Z, Huang H, et al. Improved thermal performance of Thermomyces lanuginosus GH11xylanase by engineering of an N-terminal disulfide bridge [J]. Bioresour Technol,2012,112:275-279.
    147. Kim H S, Le Q A T, Kim Y H. Development of thermostable lipase B from Candida antarctica (CalB)through in silico design employing B-factor and RosettaDesign [J]. Enzyme Microb Tech,2010,47(1-2):1-5.
    148. Tina K G, Bhadra R, Srinivasan N. PIC: Protein Interactions Calculator [J]. Nucleic Acids Res,2007,35: W473-W476.
    149. Xie Z H, Shi X J. Fast and almost100%efficiency site-directed mutagenesis by the megaprimer PCRmethod [J]. Prog Biochem Biophys,2009,36(11):1490-1494.
    150. Le Q A T, Joo J C, Yoo Y J, et al. Development of thermostable Candida antarctica lipase B throughnovel in silico design of disulfide bridge [J]. Biotechnol Bioeng,2012,109(4):867-876.
    151.刘辉.农作物秸秆低聚木糖膜分离纯化和浓缩的研究[D]:[硕士学位论文].南昌:南昌大学,
    2012.
    152. Verjans P, Dornez E, Segers M, et al. Truncated derivatives of a multidomain thermophilic glycosylhydrolase family10xylanase from Thermotoga maritima reveal structure related activity profiles andsubstrate hydrolysis patterns [J]. J Biotechnol,2010,145(2):160-167.
    153.黄家骥.酶法水解玉米芯木聚糖制备低聚木糖[D]:[硕士学位论文].无锡:江南大学,2004.
    154.张静文.玉米芯中低聚木糖提取和定性定量分析[D]:[硕士学位论文].长春:长春工业大学,
    2010.
    155. Dubois M, Gilles K, Hamilton J K, et al. A colorimetric method for the determination of sugars [J].Nature,1951,168(4265):167-167.
    156.李秀婷,孙宝国,宋焕禄等.玉米芯水不溶性木聚糖的碱法提取及酶解分析[J].中国食品学报,2010,10(5):171-176.
    157.杨瑞金,许时婴,王璋.凝胶过滤色谱法研究酶法生产低聚木糖过程中木聚糖分子结构的变化[J].中国粮油学报,2002,17(4):48-51.
    158. Aachary A A, Prapulla S G. Value addition to corncob: Production and characterization ofxylooligosaccharides from alkali pretreated lignin-saccharide complex using Aspergillus oryzaeMTCC5154[J]. Bioresour Technol,2009,100(2):991-995.
    159. Lin Y S, Tseng M J, Lee W C. Production of xylooligosaccharides using immobilized endo-xylanaseof Bacillus halodurans [J]. Process Biochem,2011,46(11):2117-2121.
    160. Chapla D, Pandit P, Shah A. Production of xylooligosaccharides from corncob xylan by fungalxylanase and their utilization by probiotics [J]. Bioresour Technol,2012,115:215-221.
    161. Yoon K Y, Woodams E E, Hang Y D. Enzymatic production of pentoses from the hemicellulosefraction of corn residues [J]. LWT-Food Sci Technol,2006,39(4):387-391.
    162. Weng X Y, Sun J Y. Hydrolysis of xylans by a thermostable hybrid xylanase expressed in Escherichiacoli [J]. Appl Biochem Microbiol,2010,46(5):511-514.
    163.王海,李里特,石波.玉米芯木聚糖和桦木木聚糖组成成分及结构的研究[J].食品科学,200425(S1):36-42.
    164. Liu M Q, Liu G F. Expression of recombinant Bacillus licheniformis xylanase A in Pichia pastoris andxylooligosaccharides released from xylans by it [J]. Protein Expres Purif,2008,57(2):101-107.
    165. Berrin J G, Juge N. Factors affecting xylanase functionality in the degradation of arabinoxylans [J].Biotechnol Lett,2008,30(7):1139-1150.
    166. Brienzo M, Carvalho W, Milagres A M F. Xylooligosaccharides production from alkali-pretreatedsugarcane bagasse using xylanases from Thermoascus aurantiacus [J]. Appl Biochem Biotechnol,2010,162(4):1195-1205.

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