Changes in the activities of serum arylamidases by injection of parathormone in rats.

Abstract

As already reported, the activities of α-L-glutamyl β-naphthylamidase, Lleucyl β-naphthylamidase, and L-Ieucinamide hydrolyzing enzyme (leucine aminopeptidase) in rat serum were changed markedly by the injection of various doses of parathormone. The effect of parathormone on the enzyme activities for the hydrolysis of other amino acid β-naphthylamides in serum was reported in this communication. Naphthylamides of 6 different amino acids were used as substrates to measure the activities. The activities in rat serum which hydrolyzed β-naphthviamides of alanine, methionine, norleucine, and phenylalanine were not changed significantly by an injection of 1200 U.S.P. parathyroid units/100g body weight, and 86, 74, 90, or 88% of controls, respectively. However, the enzyme activity for the hydrolysis of arginyl or lysyl β-naphthylamide (aminopeptidase B) was decreased to 37% or 47 % of controls by the injection of 1200 units of parathormone.