Induction of tryptophan oxygenase and tyrosine aminotransferase in mice

Abstract

The tryptophan oxygenase and tyrosine aminotransferase of mouse liver can be assayed under the same conditions found to be optimal for the rat liver enzymes. The tryptophan oxygenase existed largely as the inactive apoenzyme form in untreated or hydrocortisone-treated mice, and the injection of tryptophan caused it to become more conjugated and to increase in total amount in both intact and adrenalectomized mice. Tyrosine aminotransferase was also induced by both hydrocor-tisone and tryptophan; the former was more effective in male than in female mice. Comparison of 4 different inbred strains of mice revealed significant quantitative differences in the response of the enzymes to the inducers.