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猪肺中血管紧张素转化酶的分离纯化与性质研究
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摘要
血管紧张素转化酶(Angiotensin-I-Conveting-Enzyme,ACE)是一种膜结合的羧基外肽酶,主要存在于哺乳动物的肺部,其能够引起血管收缩,导致血压升高。本研究以新鲜猪肺为原料,通过含盐缓冲液多次匀浆粗提,同时结合DEAE+Sepharose阴离子交换层析、Phenyl-Sepharose HP疏水层析和Sephacryl S+200凝胶层析分离纯化得出ACE。SDS+PAGE结果显示该酶的分子质量约为180 kDa。运用肽质量指纹图谱对纯化的目的蛋白进行鉴定,得到二级质谱肽段17个,共293个氨基酸,与野猪(Sus scrofa)ACE序列一致性为100%,证明纯化的蛋白为ACE。酶学性质表明,该酶在最适温度约为40℃,-30℃下保存三个月酶活力仍保持稳定;最适pH约为8.0,在中性及弱碱性范围内稳定。本实验采用低成本原料,并使用钠盐匀浆粗提法代替长久沿用的高浓度硫酸铵盐析法,获得了高纯度、高价值、高稳定性的ACE,为制备功能性ACE抑制肽奠定了研究基础。
Angiotensin-converting enzyme(ACE,dipeptidyl-peptidase A,kininase II,E.C.3.4.15.1),a kind of membrane-bound carboxy exopeptidase,mainly existsin the lung of mammals and is crucial for regulating blood pressure especially since it converts the vasopressor angiotensin II from angiotensin I.Process withsodium chloridbuffer and a series of chromatographic steps including DEAE-Sepharose,Phenyl-Sepharose and Sephacryl S-200,purified ACE from pig lung with a molecular weight of approximately 180 kDa was obtained.Peptide mass fingerprinting analysis obtained 17 peptide fragments containing 293 amino acids which was 100%identical to ACE fromSiiS scrofa.The purified enzyme revealed an optimum temperature of 40℃ and retained stable activity even after 3 months of cold storage.The optimum pHof the enzyme was 8.0 andit works in pH of alkaline.ACE with high-purity,high-value,high stability was obtained by the use of low cost raw materialsand improvement of ammonium sulfate precipitation method,all this work provides the basis for ACE inhibitory peptides research.
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