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-c...

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Bibliographic Details
Published inJournal of dairy research Vol. 43; no. 1; p. 19
Main Authors Lorient, D, Linden, G
Format Journal Article
LanguageEnglish
Published England 01.02.1976
Subjects
Alkaline Phosphatase - antagonists & inhibitors
Alkaline Phosphatase - metabolism
Animals
Caseins - metabolism
Cattle
Hydrogen-Ion Concentration
Lactoglobulins - pharmacology
Magnesium - pharmacology
Milk - enzymology
Phosphates - metabolism
Zinc - pharmacology
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Summary: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.
ISSN:0022-0299
DOI:10.1017/S0022029900015557