Reactivation of alkaline phosphatases after dialysis

Abstract

The mechanism of enzyme inhibition during electrodialysis of fecal, intestinal, kidney and liver alkaline phosphatases was studied. The migration of a substance with strong reactivating properties towards the cathode during dialysis of the different phosphatases was most clearly demonstrable with the kidney enzyme. The properties of this substance were investigated and compared with certain other substances. No evidence in favor of the two-metal theory involving Zn could be obtained. The presence of 3 main components seemed to be indispensable for the normal alkaline phosphomonoesterase activity: a specific protein apo-enzyme; an organic dialyzable coenzyme; and Mg. The activation of the enzyme by Mg, and possibly certain other metals and amino acids, took place only in the presence of the dialyzable coenzyme. The differences among the alkaline phosphatases of different origins were probably due to different affinities between the apoenzyme and its coenzyme, possibly to slight variations in the nature of the apoenzyme in different phosphatases. The apoenzyme appeared to contain amino groups, which were essential for the phosphatase activity.