A Rapid Method for the Determination of Proteolytic Activities of Enzyme Preparations

A method has been described for the determination of proteolytic activities of enzyme preparations using casein as substrate. The rate of digestion is proportional to the enzyme concentration used. This relationship is utilized as a measure of the enzyme activity. One unit of activity is defined as the amount which is required to digest casein in 15 minutes at 37.5 degrees C. so that 50 per cent of the protein in 1 ml. of 0.25 per cent solution is not precipitable by trichloroacetic acid. This method has been used to determine the activity of enzymes from different sources and also used to follow the rate of activation of enzymes.