4.4 Article

Chloride Regulation of Enzyme Turnover: Application to the Role of Chloride in Photosystem II

期刊

BIOCHEMISTRY
卷 50, 期 14, 页码 2725-2734

出版社

AMER CHEMICAL SOC
DOI: 10.1021/bi2000388

关键词

-

向作者/读者索取更多资源

Chloride-dependent alpha-amylases, angiotensin-converting enzyme (ACE), and photosystem II (PSII) are activated by bound chloride. Chloride-binding sites in these enzymes contain a positively charged Arg or Lys residue crucial for chloride binding. In a-amylases and ACE, removal of chloride from the binding site triggers formation of a salt bridge between the positively charged Arg or Lys residue involved in chloride binding and a nearby carboxylate residue. The mechanism for chloride activation in ACE and chloride-dependent alpha-amylases is 2-fold: (i) correctly positioning catalytic residues or other residues involved in stabilizing the enzyme substrate complex and (ii) fine-tuning of the plc of a catalytic residue. By using examples of how chloride activates a-amylases and ACE, we can gain insight into the potential mechanisms by which chloride functions in PSII. Recent structural evidence from cyanobacterial PSII indicates that there is at least one chloride-binding site in the vicinity of the oxygen-evolving complex (OEC). Here we propose that, in the absence of chloride, a salt bridge between D2:1(317 and D1:D61 (and/or D1:E333) is formed. This can cause a conformational shift of D1:D61 and lower the pKa of this residue, making it an inefficient proton acceptor during the S-state cycle. Movement of the D1 :E333 ligand and the adjacent D1 :H332 ligand due to chloride removal could also explain the observed change in the magnetic properties of the manganese cluster in the OEC upon chloride depletion.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.4
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据