Studies on bovine hepatic fructose 1,6-diphosphatase. Substrate inhibition and the kinetic mechanism.

摘要: Abstract The kinetics of purified bovine hepatic fructose 1,6-diphosphatase have been examined at physiological pH. enzyme is inhibited by high concentrations both its substrate, 1,6-diphosphate (Fru-1,6-P2), and cofactor magnesium. Magnesium inhibits noninhibitory Fru-1,6-P2 concentrations, but inhibitory substrate magnesium activates rather than inhibits. inhibition competitive with the Ki (or Kss) for same as Kdiss (MgFru-1,6-P2)-1, indicating that forming a chelate free substrate. This suggests (MgFru-1,6-P2)-1 not true may be Fru-1,6-P2. Inhibition hyperbolic, noncompetitive respect to double reciprocal plot v versus Mg2+ concentration intersecting, sequential mechanism binding. equilibrium ordered; is, in mechanism, either or can bind first. evidence existence an allosteric site inhibition, well possible significance are discussed.