Protein degradation in health and disease. Introduction: the classification of proteinases.

Twenty years after B.S. Hartley's 1960 review, on which the present scheme for classification of the proteinases is based, most of the new information that has been obtained appears fully consistent with Hartley's views. A slight amendment is proposed of the name of the four groups of these enzymes to 'serine', 'cysteine', 'aspartic' and 'metallo'-proteinases.