ISSN:
1432-072X
Keywords:
Nitrite oxidation
;
Nitrate reduction
;
Molybdo-iron-sulfur protein
;
Molybdenum center
;
Iron-sulfur cluster
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Nitrite oxidoreductase was isolated from mixotrophically grown cells of Nitrobacter hamburgensis. The enzyme purified from heat treated membranes was homogeneous by the criteria of polyacrylamide gel electrophoresis and size exclusion chromatography. The monomeric form consisted of two subunits with Mr 115000 and 65000, respectively. The dimeric form of the enzyme contained 0.70 molybdenum, 23.0 iron, 1.76 zinc, and 0.89 copper. The catalytically active enzyme was investigated by visible and electron paramagnetic resonance spectroscopy (EPR) under oxidizing (as isolated), reducing (dithionite), and turnover (nitrite) conditions. As isolated the enzyme exhibited a complex set of EPR signals between 5–75 K, originating from several ironsulfur and molybdenum (V) centers. Addition of the substrate nitrite, or the reducing agent dithionite resulted in a set of new resonances. The molybdenum and the iron-sulfur centers of nitrite oxidoreductase from Nitrobacter hamburgensis were involved in the transformation of nitrite to nitrate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00245215
