Lysosomal proteolytic activity in the liver of growing mice

The behaviour of the activity of some lysosomal proteolytic enzymes in the liver of mice, both selected and unselected for high body growth, was follo wed during the postnatal development; The activity of cathepsin D and L, th e alanylaminopeptidase, the arginylaminopeptidase, the alpha-glucosidase an d the N-acetyl-glucosaminidase was estimated in male mice aging 21, 28, 35 and 42 days. In the liver of animals with high body gain statistic signific ant lower activities (30-50%) of all estimated enzymes were found, in compa rison to the control mice. These results confirm the statement that inhibit ion of proteolysis is an immediate mechanism in the induction of growth.