Comparative biochemical study of alkaline phosphatase isozymes in fish, amphibians, reptiles, birds and mammals

Alkaline phosphatases from the liver, kidney and intestine in various vertebrates were strongly inhibited by beryllium, 2-mercaptoethanol, potassium cyanide and EDTA. The enzymes showed various sensitivities to the inhibition by zinc and to heat denaturation at 56 degrees C for 5 min at pH 7.0. The liver and kidney enzymes showed higher sensitivity to the inhibition by L-homoarginine than by L-phenylalanine. The intestinal enzymes in higher vertebrates were more sensitive to the inhibition by L-phenylalanine than by L-homoarginine, whereas the intestinal ones in lower vertebrates showed quite similar sensitivities to both amino acids.