Abstract

A number of the commercially available enzyme preparations used in previous work on enzyme depilation have been obtained from the suppliers in crystalline form. These enzymes were tested for the following types of activity, protease (against casein and oxidised insulin), hyaluronidase, elastase, chondroitinase, amidase, amino and carboxypeptidase, collagenase, sulphatase and β-glucuronidase, in order to see if there was any correlation between the activity and the depilatory activity on sheepskins. There was a highly significant correlation (at the 0.1% level) between the depilatory activity and the proteolytic activity against both casein and oxidised insulin. In the other cases, when the enzymes did show any activity of the specified type, there was no correlation whatsoever with the depilatory activity. Evidence is presented that the only type of activity necessary for depilation to occur is a general, broad specificity proteolytic activity involving proteases of the endopeptidase type. Alcalase, one of the most highly active depilatory preparations is subjected to a variety of procedures to determine and prepare a completely homogeneous sample containing only one enzyme species. It is shown that such a homogeneous preparation can function as an extremely active depilatory, thus establishing that only one enzyme is necessary to bring about the process of depilation. The problems of preparing leather from enzyme depilated hides and skins, and the general problems of enzyme use in tanneries are discussed.