Removal of phosphate groups from casein with potato acid phosphatase.
Potato acid phosphatase (EC 3.1.3.2) was used to remove the eight phosphate groups from alphas1-casein. Unlike most acid phosphatases, which are active at pH 6.0 or below, potato acid phosphatase can catalyze the dephosphorylation of alphas1-casein at pH 7.0. Although phosphate inhibition is considerable (K1=0.42 mM phosphate), the phosphate ions produced by the dephosphorylation of casein can be removed by dialysis, allowing the reaction to go to completion. The dephosphorylated alphas1-casein is homogeneous on gel electrophoresis with a slower mobility than native alphas1-casein and has an amino acid composition which is identical to native alphas1-casein. Thus the removal of phosphate groups from casein does not alter its primary structure. Potato acid phosphatase also removed the phosphate groups from other phosphoproteins, such as beta-casein, riboflavin binding protein, pepsinogen, ovalbumin, and phosvitin.
D000135:Acid Phosphatase / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002364:Caseins; D002417:Cattle; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010750:Phosphoproteins; D010944:Plants / Q000201:enzymology*
D000596:Amino Acids; D002364:Caseins; D010750:Phosphoproteins; D000135:Acid Phosphatase