RESUMO
The effects of various chemicals were studied on the activity of purified lactate dehydrogenase [LDH] from buffalo's liver. Gossypol acetic acid, cupric and mercuric ions had completely inhibited the enzyme. Zinc showed inhibition only for reverse reaction. Lead, nickel and silver had shown more inhibition for forward reaction while cobalt produced inhibition only for forward reaction. The inhibition of reverse reaction by two metal chelators [hydroxyquinoline and dipyridyl] suggests that LDH from buffalo liver may require metal ions for its activity in reverse direction only. Oxalate also inhibited both sides of reaction and its Ki with respect to pyruvate was found to be 0.35 mM. Most of the nucleotides tested had almost no effect on the activity of LDH on either direction. Pyrophosphate and n - hexanediol also had shown no effect