Effect of Metal Ions on the Activity of Alkaline Phosphatase from Haliotis diversicolor

Alkaline phosphatase(EC 3.1.3.1)is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters.The present paper deals with the study of the effect of some kinds of metal ions on the activity of alkaline phosphatase from Haliotis diversicolor.The positive monovalent alkali metal ions(Li~+,Na~+and K~+)have no any effect on the enzyme and that the acid radicals:SO_4~(2+),Cl~-and NO_3~-do not influence the enzyme activity,either;positive bivalent alkaline-earth metal ions(Mg~(2+),Ca~(2+)and Ba~(2+))activate the enzyme and the order of the activation intensity is following:Mg~(2+)Ca~(2+)Ba~(2+).The effect of transition Mn~(2+)and Co~(2+)activate the enzyme,while Cu~(2+)and Zn~(2+)inhibit the enzyme.The activation effects of Mn~(2+)on the enzyme are of mixed type.Heavy metal ions(Hg~(2+),Ag~+,Cd~(2+)and Pb~(2+))inhibit the enzyme too.The inhibition effect of Hg~(2+)is stronger than that of Cu~(2+).The inhibition of Cu~(2+)on the enzyme appears to be a partial noncompetitive type and the inhibition constant(K_I)was determined to be 0.316 mmol/L.