Studies on Alkaline Milk Phosphatase III: A Theory for the Mechanism of Reactivation of Alkaline Milk Phosphatase in a Model System

Abstract

AbstractA hypothesis on the mechanism of the reactivation of alkaline phosphatase from cream and milk is formulated. By adding pasteurized cream to raw cream the isozyme pattern of the alkaline phosphatases was found to be characteristically changed, leading to the formation of a strong zone of β‐isozyme. This so called „β‐effect”︁ principally resembles the reactivation process and may be considered as a simple model system for this process. During pasteurization of cream a part of the outer surface layer of the fat globule membrane particularly rich in the β‐isozyme of alkaline phosphatase is dispersed into the aqueous phase. By this mechanism denatured β‐isozyme migrates into the aqueous phase of cream or milk after pasteurization. When the pasteurized extract containing the denatured β‐AP is admixed to raw cream, a renaturation of the denatured dß‐AP to renatured rß‐AP is effected under influence of the conformation of the native β‐AP and associated lipoproteins present in the membrane.