...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >The molecular structure and catalytic mechanism of a novel carboxyl peptidase from Scytalidium lignicolum
【24h】

The molecular structure and catalytic mechanism of a novel carboxyl peptidase from Scytalidium lignicolum

机译：褐藻镰刀菌新型羧基肽酶的分子结构和催化机理

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The molecular structure of the pepstatin-insensitive carboxyl peptidase from Scytalidium lignicolum, formerly known as scytalidopepsin B, was solved by multiple isomorphous replacement phasing methods and refined to an R factor of 0.230 (R-free = 0.246) at 2.1-Angstrom resolution. In addition to the structure of the unbound peptidase, the structure of a product complex of cleaved angiotensin II bound in the active site of the enzyme was also determined. We propose the name scytalidocarboxyl peptidase B (SCP-B) for this enzyme. On the basis of conserved, catalytic residues identified at the active site, we suggest the name Eqolisin for the enzyme family. The previously uninvestigated SCP-B fold is that of a beta-sandwich; each sheet has seven antiparallel strands. A tripeptide product, Ala-Ile-His, bound in the active site of SCP-B has allowed for identification of the catalytic residues and the residues in subsites S1, S2, and S3, which are important for substrate binding. The most likely hydrolytic mechanism involves nucleophilic attack of a general base (Glu-136)-activated water (OH-) on the si-face of the scissile peptide carbonyl-carbon atom to form a tetrahedral intermediate. Electrophilic assistance and oxyanion stabilization is provided by the side-chain amide of Gln-53. Protonation of the leaving-group nitrogen is accomplished by the general acid function of the protonated carboxyl group of Glu-136. [References: 37]
机译：通过多种同构置换定相方法解决了来自Scytalidium lignicolum的对胃抑素不敏感的羧基肽酶的分子结构，该结构通过多种同构置换定相方法进行了解析，并在2.1埃分辨率下精炼为R因子0.230（无R = 0.246）。除了未结合的肽酶的结构外，还测定了结合在酶的活性位点上的切割的血管紧张素II的产物复合物的结构。我们为该酶命名为“鞘氨醇羧肽酶B（SCP-B）”。根据在活性位点确定的保守催化残基，我们建议将Eqolisin命名为酶家族。之前未经调查的SCP-B褶皱是β三明治。每张纸有七个反平行链。结合在SCP-B活性位点上的三肽产物Ala-Ile-His已允许鉴定催化残基以及亚位点S1，S2和S3中的残基，这对于底物结合很重要。最可能的水解机制涉及在易裂肽羰基碳原子的si面上对一般碱基（Glu-136）活化的水（OH-）进行亲核攻击，从而形成四面体中间体。 Gln-53的侧链酰胺可提供亲电子助剂和氧阴离子稳定化作用。离去基团氮的质子化是通过Glu-136质子化羧基的一般酸官能来实现的。 [参考：37]

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