[Studies on activity and properties of alkaline phosphatase in body fluids (plasma, serum, bile) and in various organs (kidney, liver, small intestine, bones) in cattle].

Behaviour of the alkaline phosphatase (AP) present in blood serum, blood plasma, bile and extracts of organs (kidney, liver, intestinal mucosa, bone) was studied under various conditions of incubation (after preliminary heat treatment and after addition of L-phenyl-alanine). AP in serum and bile from calves and bullocks was very heat labile and did not inhibit phenylalanine much. EDTA and citrate were active inhibitors of AP, and therefore blood samples containing these anticoagulants are unsuitable for enzyme investigations. Out of four compounds tested, the substrate that was most rapidly split by AP from tissues was disodium phenylphosphate. AP activity was particularly high in kidney. The most heat-labile form of AP was that present in bone. AP in different tissues was inhibited to different extents by phenylalanine.