Roles of Three Conserved Active Site Residues of Cytochrome <i>c</i> Nitrite Reductases During the Early Steps of Nitrite Reduction.

ABSTRACT: Cytochrome c nitrite reductases (ccNiRs) catalyze reduction of nitrite to ammonium in a six-electron, eight-proton process. This report explores how the behavior of three active site ccNiR variants differs from that of the wild type enzyme (ccNiR_wt) in the presence of nitrite and a variety of electron donors. While the nitrite-loaded active site of Shewanella oneidensis ccNiR_wt could be 2-electron reduced within seconds to yield a 6-coordinate ferrous nitrosyl ({Fe(L)NO}⁷) at high applied potentials, quantitative reduction of the nitrite-loaded variants R103Q, H257Q, or Y206F required substantially stronger reductants and yielded a different product over several hours. Thus, nitrite-loaded variant reduction by a large excess of hexaammineruthe

SUBMITTER: Alam S 

PROVIDER: S-EPMC12498419 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature