陈文峰的博客分享 http://blog.sciencenet.cn/u/陈文峰 专注于根瘤菌的研究

博文

Mechanism of D-cycloserine action: alanine racemase from Escherichia coli W

已有 3760 次阅读 2007-11-29 15:49 |个人分类:微生物生理学专栏

J Bacteriol. 1972 Jun;110(3):978-87.

Mechanism of D-cycloserine action: alanine racemase from Escherichia coli W.

The antibiotic d-cycloserine is an effective inhibitor of alanine racemase. The lack of inhibition by l-cycloserine of alanine racemase from Staphylococcus aureus led Roze and Strominger to formulate the cycloserine hypothesis. This hypothesis states that d-cycloserine has the conformation required of the substrates on the enzyme surface and that l-cycloserine cannot have this conformation. Alanine racemase from Escherichia coli W has been examined to establish whether these observations are a general feature of all alanine racemases. The enzyme (molecular weight = 95,000) has Michaelis-Menten constants of 4.6 x 10(-4)m and 9.7 x 10(-4)m for d- and l-alanine, respectively. The ratio of V(max) in the d- to l-direction is 2.3. The equilibrium constant calculated from the Haldane relationship is 1.11 +/- 0.15. Both d- and l-cycloserine are competitive inhibitors with constants (K(i)) of 6.5 x 10(-4)m and 2.1 x 10(-3)m, respectively. The ratio of K(m)d-alanine to K(i)d-cycloserine is 0.71, and the ratio of K(m)l-alanine to K(i)l-cycloserine is 0.46. Since l-cycloserine is an effective inhibitor, it is concluded that the cycloserine hypothesis does not apply to the enzyme from E. coli W.

 fulltext



http://blog.sciencenet.cn/blog-3533-11802.html

上一篇:大肠杆菌中半胱氨酸合成过程中的一个酶的纯化,过表达
下一篇:气候、植物、土壤对根瘤菌能在豆科植物上结瘤的选择

0

发表评论 评论 (0 个评论)

数据加载中...

Archiver|手机版|科学网 ( 京ICP备14006957 )

GMT+8, 2019-8-22 17:02

Powered by ScienceNet.cn

Copyright © 2007- 中国科学报社

返回顶部