Evidence that the type 2 copper centers are the site of nitrite reduction by Achromobacter cycloclastes nitrite reductase.
Methods have been developed for selective depletion and reconstitution of the Type 2 Cu (non-blue) sites in the nitrite reductase from A. cycloclastes, resulting in preparations ranging from 0.5 to 2.6 Type Cu per trimer; the Type 1 Cu content is invariant at 3.0 per trimer. The activity of the enzyme is directly proportional to the Type 2 content as measured by direct metal determination or by analysis of the EPR spectra. These results indicate that an earlier report that the A. cycloclastes enzyme contains only Type 1 Cu sites is incorrect, and that the Type 2 Cu centers constitute the site at which NO2- is reduced. Furthermore, they suggest that other Cu nitrite reductases that are reported to contain only Type 1 Cu sites and exhibit relatively low activity may actually be largely Type 2 Cu-depleted forms of the enzymes.
Libby
E
E
Department of Chemistry, University of Virginia, Charlottesville 22901.
Averill
B A
BA
D000421:Alcaligenes / Q000201:enzymology*; D001665:Binding Sites; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D009572:Nitrite Reductases / Q000737:chemistry / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D013045:Species Specificity
D009573:Nitrites; D003300:Copper; D009572:Nitrite Reductases