Influence of Photoirradiation on the Oxidation-Reduction State of Thioredoxin Reductase
Year: 1968
Type: article
Abstract: The flavin semiquinone form of thioredoxin reductase can be produced in high yield either by photoirradiation in the presence of excess ethylenediaminetetraacetate or, much more rapidly, by exposure of partially reduced enzyme to light. Extinction coefficients of the semiquinone have been derived at critical wave lengths. The semiquinone forms produced are of the blue type, i.e. they are neutral semiquinones. Electron paramagnetic resonance determinations confirm the free radical nature of the species. Two different spectra of the semiquinone have been observed. The shift from one type to the other can be effected in several ways; evidence is given which indicates that the shift in the semiquinone band is due to a change in the environment of the flavin moiety determined by the reduction state of the second oxido-reductively active group of thioredoxin reductase, a disulfide bridge. The flavin semiquinone of this enzyme cannot be reoxidized by thioredoxin or reduced by TPNH, and thus cannot be involved in the catalytic reaction.
Source: Journal of Biological Chemistry
Authors: G Zanetti, C H Williams, V Massey
Institution: University of Michigan
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1514163703