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Determination of the g‐matrix orientation in flavin radicals by high‐field/high‐frequency electron‐nuclear double resonance
Author(s) -
Kay Christopher W. M.,
Schleicher Erik,
Hitomi Kenichi,
Todo Takeshi,
Bittl Robert,
Weber Stefan
Publication year - 2005
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1667
Subject(s) - chemistry , flavin group , electron paramagnetic resonance , nuclear magnetic resonance , electron nuclear double resonance , resonance (particle physics) , atomic physics , physics , enzyme , biochemistry
A high‐microwave‐frequency/high‐magnetic‐field pulsed electron‐nuclear double resonance (ENDOR) study performed at 94 GHz on the flavin semiquinone cofactor of Xenopus laevis (6–4) photolyase in its neutral radical state is presented. Although the principal values of the flavin radical's g‐matrix are not fully resolved in the 94‐GHz EPR spectrum in a nonoriented sample, the orientation of the principal axes of g is obtained by exploiting the orientation selection of the proton ENDOR signals from the methyl protons at C‐8α and the deuteron ENDOR signals from D‐5 in an enzyme sample in deuterated buffer. This procedure for assigning the orientation of g relative to the molecular frame makes use of commercially available ENDOR instrumentation without the necessity to perform single‐crystal studies. Copyright © 2005 John Wiley & Sons, Ltd.