Dephosphorylation of bovine casein by milk alkaline phosphatase.
The pH of optimum activity of alkaline phosphatase from cow's milk depended on the substrate, being 10-1 for rho-nitrophenylphosphate, 8-6 for phosphoserine, 8-0 for phosvitin and 6-8 for casein. Individual casein components were dephosphorylated more rapidly than mixtures of alphas- and beta-caseins or of alphas-, beta-and kappa-caseins and micellar casein. Mixtures of 2 components involving kappa-casein were more readily dephosphorylated than alphas- and beta-casein mixtures. At pH 6-8, lactose, whey proteins and phosphate ions had an inhibitory effect. beta-Lactoglobulin had an inhibitory effect only when the pH of the reaction was lower than the optimum pH value of the enzyme. Mg2+ and Zn2+ were not inhibitory. The optimum conditions for dephosphorylation of casein are described.
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002364:Caseins / Q000378:metabolism*; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008892:Milk / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
D002364:Caseins; D007782:Lactoglobulins; D010710:Phosphates; D000469:Alkaline Phosphatase; D008274:Magnesium; D015032:Zinc