On the prosthetic group(s) of component II from nitrogenase. EPR of the Fe-protein from Azotobacter vinelandii.
The EPR spectrum of the reduced Fe-protein from nitrogenase has been reinvestigated. The dependences on temperature, microwave power, and microwave frequency all suggest that the observed signal represents a magnetically isolated [4Fe-4S]1+(2+;1+) cluster. Also, the signal can be simulated assuming a simple, g-strained S = 1/2 system. However, the integrated intensity amounts to no more than 0.2 spins per protein molecule. It is, therefore, impossible that Fe-protein preparations contain a single type of [4Fe-4S] cluster.
Hagen
W R
WR
Dunham
W R
WR
Braaksma
A
A
Haaker
H
H
D001395:Azotobacter / Q000201:enzymology*; D003201:Computers; D004578:Electron Spin Resonance Spectroscopy; D008872:Microwaves; D009591:Nitrogenase; D013696:Temperature
D009591:Nitrogenase