Showing papers by "Vadim N. Gladyshev published in 1997"
TL;DR: Crystal structures of the oxidized and reduced formate dehydrogenase H form have been determined, revealing a four-domain αβ structure with the molybdenum directly coordinated to selenium and both MGD cofactors, which suggest a reaction mechanism that directly involves SeCys140 and His141 in proton abstraction and the Molybdopterin, Lys44, and the Fe4S4 cluster in electron transfer.
Abstract: Formate dehydrogenase H from Escherichia coli contains selenocysteine (SeCys), molybdenum, two molybdopterin guanine dinucleotide (MGD) cofactors, and an Fe4S4 cluster at the active site and catalyzes the two-electron oxidation of formate to carbon dioxide. The crystal structures of the oxidized [Mo(VI), Fe4S4(ox)] form of formate dehydrogenase H (with and without bound inhibitor) and the reduced [Mo(IV), Fe4S4(red)] form have been determined, revealing a four-domain alphabeta structure with the molybdenum directly coordinated to selenium and both MGD cofactors. These structures suggest a reaction mechanism that directly involves SeCys140 and His141 in proton abstraction and the molybdenum, molybdopterin, Lys44, and the Fe4S4 cluster in electron transfer.
534 citations
Journal Article•
TL;DR: Three peaks of the catalytic activity were found on the plot of activity versus surfactant hydration degree which corresponded to functions of the enzyme in various oligomeric forms: monomeric, dimeric, and octameric.
Abstract: Formate dehydrogenases from the methylotrophic bacteria Pseudomonas sp. 101 and Mycobacterium vaccae N10 were studied in a system of Aerosol OT reversed micelles in octane. Three peaks of the catalytic activity were found on the plot of activity versus surfactant hydration degree (the size of the micellar inner cavity) which corresponded to functions of the enzyme in various oligomeric forms: monomeric, dimeric, and octameric. Kinetic data were confirmed by results of sedimentation analysis. The enzyme was chemically modified by a bifunctional reagent (dimethyl suberimidate) to obtain a catalytically active non-dissociating dimeric molecule of formate dehydrogenase. In the case of the covalently-linked non-dissociating dimeric enzyme, the peak which corresponded to the monomeric form of the enzyme was found to disappear from the catalytic activity curve.
2 citations