Acid proteinase of chicken liver. Purification and properties

Abstract

A method for purifying the haemoglobinolitic activity to acid pH in chicken liver is described.The purified preparation contains cathespin D activity since it is inhibited by diazoacetyl-DL-norleucine methylester in the presence of cupric ions, while thiol-enzyme reagents do not affect it.The molecular weight of the enzyme is approximately 40,000–45,000 and the pH optimum against haemoglobin and bovine serum albumin is 3.5-03.7.The rate of degradation of albumin and casein is much less than that of haemoglobin.Cathepsin D preparations with different purification degrees, exhibit a similar percentage of activation at acid pH; the highest activation is observed at pH 3.1-03.3.