Automated colorimetric determination of acid proteinase activity in fermentation samples using a trinitrobenzenesulphonic acid reagent

Abstract

An automated method for the determination of acid proteinase activity has been developed. The enzyme is incubated with a haemoglobin substrate after which the reaction solution is dialysed. The concentration of the liberated amino acids and peptides is determined by reaction with a trinitrobenzenesulphonic acid reagent. The technical parameters of the process and the general analytical conditions have been optimised. The method offers great advantages in its flexibility of selecting substrate and buffer independently of the conditions for the colour reaction. The final result is an automated method with high sensitivity, precision and speed. The sensitivity of the colour reaction is 1 mg l^–1 of nitrogen from leucine.