Effects of age, body size and growth hormone on level of tryptophan peroxidase-oxidase in rat liver

¹ Department of Biological Chemistry, Harvard Medical School and the Cancer Research Institute of the New England Deaconess Hospital, Boston, Massachusetts

The specific activity of rat liver tryptophan peroxidase increased with age, and at 400 days was more than double the level at 38 days of age. The amount of enzyme per 100 gm body weight also increased significantly. This change of enzyme activity with age was attributed to a substrate-induced enzyme adaptation occurring under physiological conditions caused by the tryptophan available for catabolism as growth slowed. Bovine growth hormone injections increased the level of the enzyme in rats.