Bovine milk protease

Abstract

Summary Milk protease, the naturally occurring proteolytic enzyme from fresh raw bovine milk, was purified 629-fold. Purification methods are described which included acid precipitation, ion-exchange and gel chromatography and ammonium sulphate fractionation. It was necessary to use a large-scale purification as the amounts of enzyme in milk are very low. The basic properties of the enzyme were elucidated from experiments on this partially purified fraction. Under the conditions of assay these showed a wide pH optimum from 6·5 to 9·0 and a temperature optimum of 37°C. The protease was fairly heat stable, the stability being pH dependent. The source of the enzyme appeared to be the mammary gland, where the enzyme was also detected.