Siroheme-containing sulfite reductase: A density functional investigation of the mechanism

Siroheme‐containing sulfite reductases (SiR) catalyze the six‐electron reduction of sulfite to sulfide via a mechanism involving sulfite binding at the heme iron. The exact sequence in which the required electrons and protons are delivered to the heme‐bound sulfite has received little attention to d...

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Bibliographic Details
Published in:International journal of quantum chemistry 2012-02, Vol.112 (3), p.900-908
Main Authors: Silaghi-Dumitrescu, Radu, Makarov, Sergei V.
Format: Article
Language:English
Subjects:
DFT
heme
siroheme
sulfite reductase
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Summary:Siroheme‐containing sulfite reductases (SiR) catalyze the six‐electron reduction of sulfite to sulfide via a mechanism involving sulfite binding at the heme iron. The exact sequence in which the required electrons and protons are delivered to the heme‐bound sulfite has received little attention to date. Here, a detailed account is given of these steps, based on density functional theory, thus providing data for the first attempt to draw a detailed picture of sulfite reduction in SiR by theoretical methods. Parallels are shown with reduction of other small molecules at heme centers: dioxygen (including generation of sulfide high‐valent iron centers akin to hemoproteins Compounds I and II), nitrite (including linkage isomerism akin to the nitro/nitrito known for nitrite reducing proteins), or nitric oxide. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
ISSN:0020-7608
1097-461X
DOI:10.1002/qua.23038