Amino acid-p-nitroanilide and -beta-naphthylamide cleaving activities in rat serum

Determination of proteolytic activities gains increasing importance for the diagnosis of various pathologic conditions. Many questions can only be solved with the aid of experiments with animals. In preparation of such studies the pattern of the enzymatic hydrolysis of 20 amino acid-p-nitroanilides and one -beta-naphthylamide by normal rat serum was measured. The pH dependences of the single reactions are reported as well as their sensitivity to the action of ethylenediaminetetraacetic acid, dithioerithrol, and puromycin. Additionally, it is shown that collecting of the blood by cardiac puncture and preparation of the native plasma is the best way to get reproducible results.