Studies on alkaline phosphatase. Phosphorylation of calf-intestinal alkaline phosphatase by 32P-labelled pyrophosphate.
1. A purified preparation of alkaline phosphatase from calf-intestinal mucosa was phosphorylated by (32)P-labelled PP(i) at a serine residue on the enzyme. Under the conditions employed, up to 0.15mum-labelled sites were obtained from 1mum-[(32)P]PP(i). 2. The phosphorylated enzyme was labile, the rate of dephosphorylation being similar to the overall rate of substrate hydrolysis. 3. A stopped-flow technique was used to determine the number of phosphomonoesterase active sites, which agreed with the number of (32)P-labelled sites. 4. It is concluded that calf-intestinal alkaline phosphatase is both a phosphomonoesterase and a pyrophosphatase.
D000469:Alkaline Phosphatase; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D011756:Diphosphates; D004950:Esterases; D005453:Fluorescence; D007413:Intestinal Mucosa / Q000201:enzymology*; D007700:Kinetics; D010759:Phosphorus Isotopes; D011755:Pyrophosphatases
D011756:Diphosphates; D010759:Phosphorus Isotopes; D004950:Esterases; D000469:Alkaline Phosphatase; D011755:Pyrophosphatases