The nitrite oxidizing system of Nitrobacter winogradskyi.
FEMS Microbiol Rev
; 4(4): 259-70, 1988 Dec.
Article
em En
| MEDLINE
| ID: mdl-2856189
ABSTRACT
Cytochrome components which participate in the oxidation of nitrite in Nitrobacter winogradskyi have been highly purified and their properties studied in detail. Cytochrome a1c1 is an iron-sulphur molybdoenzyme which has haems a and c and acts as a nitrite-cytochrome c oxidoreductase. Cytochrome c-550 is homologous to eukaryotic cytochrome c and acts as the electron mediator between cytochrome a1c1 and aa3-type cytochrome c oxidase. The oxidase is composed of two kinds of subunits, has two molecules of haem a and two atoms of copper in the molecule, and oxidizes actively eukaryotic ferrocytochrome c as well as its own ferrocytochrome c-550. Further, a flavoenzyme has been obtained which has transhydrogenase activity and catalyses reduction of NADP+ with benzylviologen radical. This enzyme may be responsible for production of NADPH in N. winogradskyi. The electron transfer against redox potential from NO2- to cytochrome c could be pushed through prompt removal by cytochrome aa3 of H+ formed by the dehydrogenation of NO2- + H2O. As cytochrome c in anaerobically kept cell-free extracts is rapidly reduced on addition of NO2-, a membrane potential does not seem necessary for the reduction of cytochrome c by cytochrome a1c1 with NO2- in vivo.
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Base de dados:
MEDLINE
Assunto principal:
Nitritos
/
Nitrobacter
Idioma:
En
Ano de publicação:
1988
Tipo de documento:
Article