Kinetics of Hydrolysis of p-Nitrophenyl Phosphate by Fowl Plasma Alkaline Phosphatase

THE rapid hydrolysis of p-nitrophenyl phosphate (King and Delory, 1939) and the high extinction coefficients of the p-nitrophenol ion, one of the products of hydrolysis, were utilized by Bessey et al. (1946) in the development of a simple procedure for measuring alkaline phosphatase activity in minute quantities in human serum. Our interest in p-nitrophenyl phosphate was the possibility of its use in measuring quantitatively changes in plasma alkaline phosphatase in the same birds over long periods during the growth of chicks and egg production by hens. Although p-nitrophenyl phosphate has been used as the substrate for the determination of phosphatase of tissues of a number of species, including fowl (Bell, 1960, 1964; Bell and Sillers, 1962; Hurwitz and Griminger, 1961; Tanabe and Wilcox, 1961), very little has been published on the kinetics of hydrolysis of this compound by alkaline phosphatase of chicken plasma. The present paper describes studies directed toward…