Vanadium as an inhibitor of plant and mammalian peroxidases
Vanadate ions are shown to inhibit horseradish, squash, and rat intestinal peroxidases by following the reaction spectrophotometrically in a wide range of vanadate concentrations. I(50) in phosphate buffer was 43, 9.4 and 535 micro-M, respectively. No inhibitory effect is found on cow milk lactoperoxidase and beef liver catalase. Gel filtration of peroxidases in the presence of vanadate, as carried out by radioactive 48V for horseradish peroxidases (either in aerobic or anoxic conditions) and neutron activation analysis (NAA) for squash peroxidase, demonstrates a binding of vanadium to these enzymes in stoichiometric amounts. Electron paramagnetic resonance spectra of the eluted peaks for the former peroxidase indicate that vanadium is in the +5 oxidation state, but an equilibrium between V (V) and V (IV) in the assay conditions cannot be discarded. Although the inhibitory mechanism remains obscure, some hypotheses are considered. The potential implications that the inhibitory effect of vanadium might have on plant and animal metabolism are also discussed.
Bibliographic Reference: Article: Biological Trace Element Research, Vol. 23 (1990) pp. 151-164
Record Number: 199011148 / Last updated on: 1994-12-01
Original language: en
Available languages: en