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Electron paramagnetic resonance and magnetic circular dichroism studies of a hexa‐heme nitrite reductase from Wolinella succinogenes
Author(s) -
Blackmore Richard S.,
Brittain Thomas,
Gadsby Paul M.A.,
Greenwood Colin,
Thomson Andrew J.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81225-5
Subject(s) - chemistry , heme , electron paramagnetic resonance , magnetic circular dichroism , ferric , hexa , circular dichroism , histidine , nuclear magnetic resonance , nitrite reductase , crystallography , stereochemistry , enzyme , inorganic chemistry , biochemistry , spectral line , physics , nitrate reductase , astronomy
The nature of the heme centers in the hexa‐heme dissimilatory nitrite reductase from the bacterium Wolinella succinogenes has been investigated with EPR and magnetic circular dichroism spectroscopy. The EPR spectrum of the ferric enzyme is complex showing, in addition to magnetically isolated low‐spin ferric hemes with g values of 2.93, 2.3 and 1.48, two sets of signals at g = 10.3, 3.7 and 4.8, 3.21, which we assign to two pairs of exchange coupled hemes. The MCD spectra show that the isolated hemes are bis‐histidine coordinated and that there is one high‐spin ferric heme. The exchange coupling is lost on treatment with SDS.