Magnetization of the sulfite and nitrite complexes of oxidized sulfite and nitrite reductases: EPR silent spin S = 1/2 states.
The saturation magnetizations of the sulfite complex of oxidized sulfite reductase and the nitrite complex of oxidized nitrite reductase have been measured to determine their spin state. Each shows the saturation magnetization signal of a spin S = 1/2 state with sigma g2 = 16, which is typical of low-spin ferrihemes. However, the EPR spectra of these complexes lack the expected signal intensity of a spin S = 1/2 state. Indeed, one of these complexes is EPR silent. The reasons for this unexpectedly low EPR signal intensity are considered.
Day
E P
EP
Gray Freshwater Biological Institute, University of Minnesota, Navarre 55392.
Peterson
J
J
Bonvoisin
J J
JJ
Young
L J
LJ
Wilkerson
J O
JO
Siegel
L M
LM
D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008280:Magnetics; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009572:Nitrite Reductases / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000378:metabolism*; D010944:Plants / Q000201:enzymology; D013447:Sulfites / Q000378:metabolism*
D009573:Nitrites; D013447:Sulfites; D010088:Oxidoreductases; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases; D050862:Oxidoreductases Acting on Sulfur Group Donors