期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 378, 期 2, 页码 353-361出版社
ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2008.01.097
关键词
nitrite reductase; electron gating; ordered mechanism; XAS; radiation damage
资金
- Biotechnology and Biological Sciences Research Council [BBE0019711, BB/E001971/1, BBD0162901] Funding Source: Medline
- BBSRC [BB/E001971/1] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BB/E001971/1] Funding Source: researchfish
Nitrite reductases are key enzymes that perform the first committed step in the denitrification process and reduce nitrite to nitric oxide. In copper nitrite reductases, an electron is delivered from the type I copper (T1Cu) centre to the type 2 copper (T2Cu) centre where catalysis occurs. Despite significant structural and mechanistic studies, it remains controversial whether the substrates, nitrite, electron and proton are utilised in an ordered or random manner. We have used crystallography, together with online X-ray absorption spectroscopy and optical spectroscopy, to show that X-rays rapidly and selectively photoreduce the T1Cu centre, but that the T2Cu centre does not photoreduce directly over a typical crystallographic data collection time. Furthermore, internal electron transfer between the T1Cu and T2Cu centres does not occur, and the T2Cu centre remains oxidised. These data unambiguously demonstrate an 'ordered' mechanism in which electron transfer is gated by binding of nitrite to the T2Cu. Furthermore, the use of online multiple spectroscopic techniques shows their value in assessing radiation-induced redox changes at different metal sites and demonstrates the importance of ensuring the correct status of redox centres in a crystal structure determination. Here, optical spectroscopy has shown a very high sensitivity for detecting the change in T1Cu redox state, while X-ray absorption spectroscopy has reported on the redox status of the T2Cu site, as this centre has no detectable optical absorption. (c) 2008 Elsevier Ltd. All rights reserved.
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。
推荐
暂无数据