Proteins and isozymes of esterases and cholinesterases from sera of different species

Abstract

Serum proteins of the human, cat, rabbit, monkey and rat were separated by starch gel electrophoresis and in addition to protein, cholinesterase, esterase and proteolytic activities were determined. In human serum, as many as 7 esterases were visualized with thiocholine esters. The major band of activity was only partially sensitive to physostigmine. No abnormal cholinesterase pattern was apparent in 7 cases of myasthenia gravis. The patterns of esterase activities in the species studied showed conspicuous differences. Except in the monkey, some activity was associated with the albumin fraction. In human sera, with α-naphthyl propionate and a-naphthyl butyrate as substrates, a pre-albumin band of activity could be elicited. This was not present when α-naphthyl acetate was used. In different species, the resistance and sensitivity of similar enzymes to the inhibitors employed was highly variable. In human serum proteolytic activity developed with N-benzoyl- dl-arginine- β-naphthylamide included at least 2 zones of activity which did not react with thiocholine and naphthyl esters. The partial inhibition by physostigmine of the major band of activity developed in human serum with thiocholine and naphthyl esters is noted and its significance is discussed.