Nonreductive interaction of vanadate with an enzyme containing a thiol group in the active site: glycerol-3-phosphate dehydrogenase

Abstract

The inhibitory effects of vanadium(V) were determined on the oxidation of glycerol 3-phosphate (G3P) catalyzed by glycerol-3-phosphate dehydrogenase (G3PDH), an enzyme with a thiol group in the active site. G3PDH from rabbit muscle was inhibited by vanadate, and the active inhibiting species were found to be the vanadate dimer and/or tetramer. The dimer was a sufficiently weak inhibitor at pH 7.4 with respect to G3P; the tetramer could account for all the observed inhibition. The tetramer was a competitive inhibitor with respect to G3P with a Ki of 0.12 mM. Both the dimer and tetramer were noncompetitive inhibitors at pH 7.4 with respect to NAD with Ki's of 0.36 mM and 0.67 mM. G3PDH inhibited by vanadate was reactivated when EDTA complexed the vanadate. The reactivation occurred even after extended periods of incubation of G3PDH and vanadate, suggesting that the inhibition is reversible despite the thiol group in the active site. Analogous reactivation is also observed with glyceraldehyde-3-phosphate dehydrogenase (Gly3PDH). Gly3PDH is an enzyme that previously had been reported to undergo redox chemistry with vanadate. The work described in this paper suggests vanadate will not necessarily undergo redox chemistry with enzymes containing thiol groups exposed on the surface of the protein.

Decavanadate (V10O286-) and oxovanadates: Oxometalates with many biological activities

“…This and other studies illustrate how useful 51 V NMR spectroscopy is to determine the vanadate species responsible for the interactions with a particular protein or form of a protein [1,30,32,45,84]. For instance, with the SR Ca 2+ -ATPase, it was suggested that monomeric vanadate inhibits the enzyme activity [94] and the vanadate oligomers interact particularly with the E2 conformation of the enzyme [97].…”

“…1) is a more potent inhibitor than the vanadate (V 1 ) was reported for 6-phosphogluconate dehydrogenase [63] almost two decades ago. This investigation was followed up with a study of glucose-6-phosphate dehydrogenase [81] and a number of other enzymes [4,[82][83][84][85][86]. Since then many observations have followed, documenting the specific interactions between various proteins and different oxovanadate anions [4,27,45].…”

Vanadium and proteins: Uptake, transport, structure, activity and function

“…mild competitive inhibition of glucose-6-phosphate dehydrogenase [472] [473] and 1,6-bisphosphate fructose aldolase from rabbit muscle [474] and a non-competitive inhibitor of rabbit muscle glycerol-3-phosphate dehydrogenase [475].…”

Pulmonary Immunotoxic Potentials of Metals Are Governed by Select Physicochemical Properties: Vanadium Agents

“…These and other studies indicated that the mode of action of V varied with the agent employed. Both animal (Crans et al, 2004;Buglyo et al, 2005;Thompson et al, 2006) and in vitro studies (Crans et al, 1990(Crans et al, , 1996Crans and Simone, 1991) noted differential effects from V agents with varying forms, redox states, or coordinated ligands.…”