• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The biochemical journal >S-Adenosylhomocysteine hydrolase from human placenta. Affinity purification and characterization
【24h】

S-Adenosylhomocysteine hydrolase from human placenta. Affinity purification and characterization

机译：人胎盘的S-腺囊肌细胞水解酶。亲和纯化和表征

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

pS-Adenosylhomocysteine hydrolase (EC 3.3.1.1) was purified to homogeneity from human placenta by using S-adenosylhomocysteine-agarose affinity chromatography. The enzyme is a tetramer with a native Mr of 189 000 and subunit Mr of 47 000-48 000; there were nine cysteine residues per subunit and no disulphide bonds. The pI was 5.7. H.p.l.c. analysis revealed that the enzyme contained four molecules of tightly bound cofactor (NAD) per tetramer, of which 10-50% was in the reduced form. The enzyme had four binding sites per tetramer for adenosine, of which 10-35% were found to be occupied. Two types of adenosine-binding sites could be distinguished on the basis of differences in rates of dissociation of the enzyme-adenosine complex, and by examining binding of adenosine at 0 degree C and 37 degrees C. The enzyme catalysed the interconversion of adenosine and 4′,5′-dehydroadenosine; the equilibrium constant for this reaction was 2.1 and favoured 4′,5′-dehydroadenosine formation. Variability in the specific activity of preparations of S-adenosylhomocysteine hydrolase was related to the NAD+/NADH ratio of the preparation. The capacity to bind radioactively labelled adenosine depended on the adenosine content of the purified enzyme. The rate of adenosine binding and the sensitivity of S-adenosylhomocysteine hydrolase to inactivation by adenosine were both diminished in the absence of dithiothreitol./p
机译：通过使用S-腺苷半导体 - 琼脂糖亲和层析，从人胎盘纯化S-腺囊肌细胞水解酶（EC 3.3.1.1）以均匀性。酶是一种具有189 000和47 000-48 000的天然MR的四聚体;每亚基有九个半胱氨酸残基，没有二硫键。 pi是5.7。 H.P.L.C.分析表明，酶含有四个紧密结合的辅因子（NAD）的四分色谱，其中10-50％以还原形式。酶为每四聚体具有四个结合位点，用于腺苷，其中发现10-35％占用。可以基于酶 - 腺苷复合物的解离率的差异来区分两种类型的腺苷结合位点，并通过在0℃和37℃下检查腺苷的结合。酶催化了腺苷和4的相互互连'，5'-脱氢纳米苷;该反应的平衡常数为2.1并优选4'，5'-脱氢诺核苷酸形成。 S-腺苷二胞内半胱氨酸水解酶制剂的具体活性的可变性与制剂的NAD + / NADH比有关。放射性标记的腺苷结合的能力取决于纯化酶的腺苷含量。在不存在二硫代酚醇的情况下，腺苷结合与腺苷灭活的腺苷结合和S-腺瘤肌细胞酶的敏感性均减少。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号