title: On the prosthetic group(s) of component II from nitrogenase. EPR of the Fe-protein from Azotobacter vinelandii.
abstract: 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.
authors.forename: W R
authors.initials: WR
authors.lastname: Hagen
authors.forename: W R
authors.initials: WR
authors.lastname: Dunham
authors.forename: A
authors.initials: A
authors.lastname: Braaksma
authors.forename: H
authors.initials: H
authors.lastname: Haaker
mesh_terms: D001395:Azotobacter / Q000201:enzymology*; D003201:Computers; D004578:Electron Spin Resonance Spectroscopy; D008872:Microwaves; D009591:Nitrogenase; D013696:Temperature
chemical_list: D009591:Nitrogenase