Phosvitin phosphate content. Implications for protein kinase assay.
The maximal rates of the protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) reaction studied with chicken egg yolk phosvitin as substrate are dependent on the level of dephosphorylation of phosvitin. 30 per cent dephospho-phosvitin gives the optimal initial rates. With varying levels of dephosphorylation, the apparent Km for the substrate also changes in a biphasic manner. If this factor is taken into account, and a suitable adjustment is made for the concentration of dephospho-phosvitin in the reaction it is possible to achieve maximal rates for the kinase reaction with phosvitin preparations of varying levels of dephosphorylation. Such a consideration is important for comparing the results of protein kinase studies using phosvitin as the substrate.
D000255:Adenosine Triphosphate; D000818:Animals; D002645:Chickens; D004527:Egg Proteins / Q000032:analysis*; D007700:Kinetics; D010710:Phosphates; D010750:Phosphoproteins / Q000032:analysis*; D010761:Phosphorus Radioisotopes; D011494:Protein Kinases / Q000378:metabolism*
D004527:Egg Proteins; D010710:Phosphates; D010750:Phosphoproteins; D010761:Phosphorus Radioisotopes; D000255:Adenosine Triphosphate; D011494:Protein Kinases