Kinetic studies on alkaline phosphatase from liver of the baboon, Papio ursinus

Abstract

1. 1. Alkaline phosphatase was partially purified from livers of baboons that had undergone transplant operations and had raised enzyme levels. 2. 2. The Michaelis constants for p-nitrophenyl phosphate at pH 10·17 and 9·0 and for phenolphthalein monophosphate at pH 9·9 were 0·44, and 2·71 mM respectively. 3. 3. The enzyme was inhibited uncompetitively by l(+)-alanine, l(-)-phenylalanine, imidazole, l(+)-leucine, l(+)-lysine, l(+)-arginine and l(+)-homoarginine; the compounds are listed in order of increasing inhibitory capacity. 4. 4. l(+)-Cysteine and l(-)-histidine inhibited non-competitively. 5. 5. Magnesium ions activated the enzyme, whilst EDTA was inhibitory. 6. 6. The time for half-inactivation of this enzyme at 58° C. was 32 minutes. 7. 7. The isoelectric point was pH 4·3-4·6. © 1973.