Stimulation of human erythrocyte 2,3-bisphosphoglycerate phosphatase by vanadate

The rates of vanadate-stimulated hydrolysis of 2,3-bisphosphoglycerate in metabolically competent erythrocytes and in hemolysates were determined from data on time courses up to 35 min employing 31P nuclear magnetic resonance spectroscopy. The enhanced rate of hydrolysis of the bisphosphate was attributed principally to the activation of the phosphatase activity of 2,3-bisphosphoglycerate synthase both in cell suspensions and in hemolysates. Information on the concentrations of vanadate and vanadyl present in the preparations was obtained employing 51V nuclear magnetic resonance spectroscopy and electron paramagnetic resonance spectroscopy. Redox reactions involving vanadium ions appeared to be important in establishing the final equilibrium concentrations of the oxy- and oxo-ions (vanadate and vanadyl, respectively), but the data suggested that the activation of the enzyme resulted from direct action of the vanadium ions on the enzyme and not as a consequence of the alteration in the equilibrium of intracellular oxidants and reductants.