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Glutathione Peroxidase Revisited—Simulation of the Catalytic Cycle by Computer-Assisted Molecular Modelling 被引量:6
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作者 k. -d. aumann N. BEDORF +3 位作者 R. BRIGELIUS-FLOHED D. SCHOMBURG AND L. FLOHE(Gesellschaft fur Biotechnologische Forschung mbH (GBF) Mascheroder Weg 1, D-38124 Braunschweig, Germany Deutsches Institut fur Ernahrungsforschung (DIfE) Arthur-Scheunert-Allee 114 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 1997年第2期136-155,共20页
Glutathione peroxidase, the first example of selenoproteins identified in mammals, was subjected to force field calculations and molecular dynamics in order to enable a clearer comprehension of enzymatic selenium cata... Glutathione peroxidase, the first example of selenoproteins identified in mammals, was subjected to force field calculations and molecular dynamics in order to enable a clearer comprehension of enzymatic selenium catalysis. Starting from the established X-ray structure of bovine GPX, all kinetically defined intermediates and enzyme substrate complexes were modelled. The models thus obtained support the hypothesis that the essential steps of the catalysis are three distinct redox changes of the active site selenium which, in the ground state, presents itself at the surface of selenoperoxidases as the center of a characteristic triad built by selenocysteine, glutarnine and tryptophan. In GPX, four arginine residues and a lysine residue provide an electrostatic architecture which, in each reductive step, directs the donor substrate GSH towards the catalytic center in such a way that 1ts sulfhydryl group must react with the selenium moiety. To this end, different equally efficient modes of substrate binding appear possible. The models are consistent with substrate specificity data, kinetic pattern and other functional characteristics of the enzyme. Comparison of molecular models of GPX with those of other members of the GPX superfamily reveals that the cosubstrate binding mechanisrns are unique for the classical type of cytosolic glutathione peroxidases but cannot operate e. g. in plasma GPX and phospholipid hydroperoxide GPX. The structural differences between the selenoperoxidases, shown to be relevant to their specificities, are discussed in terms of functional diversification within the GPX superfamily 展开更多
关键词 GPX Glutathione Peroxidase Revisited Simulation of the Catalytic Cycle by Computer-Assisted Molecular Modelling
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