ISSN:
1432-072X
Keywords:
Nitrite reductase
;
Electron transport
;
Wolinella succinogenes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Wolinella succinogenes grown with nitrate as terminal electron acceptor contains two nitrite reductases as measured with the donor viologen radical, one in the cytoplasm and the other integrated in the cytoplasmic membrane. The fumarate-grown bacteria contain only the membraneous species. The isolated membraneous enzyme consists of a single polypeptide chain (M r 63,000) carrying 4 hemeC groups and probably an iron-sulphur cluster as prosthetic groups. The enzyme amounts to about 1% of the total membrane protein. The isolated enzyme catalyses the reduction of nitrite to ammonium without accumulation of significant amounts of intermediates or alternative products. The Michaelis constant for nitrite was 0.1 mM and the turnover number of the hemeC 1.5 · 105 electrons per min at 37°C. The viologen-reactive site of the enzyme in the membrane is oriented towards the cytoplasm. When the isolated enzyme is incorporated into liposomes, the viologen-as well as the nitrite-reactive site is exposed to thooutside. The cytoplasmic membrane contains a second hemeC protein (M r 22,000) which may represent a cytochrome c.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00446982
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