Pattern of Adaptive Control of Levels of Rat Liver Tryptophan Transaminase

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Science  19 Jun 1959:
Vol. 129, Issue 3364, pp. 1672-1673
DOI: 10.1126/science.129.3364.1672


The dual control by substrate and hormone of the level of a third adaptive enzyme in animals is described. Injections of hydrocortisone or the substrate tryptophan increased the level of the liver tryptophan-α-ketoglutarate transaminase of intact rats within 5 hours. In adrenalectomized rats this enzyme level was increased by hydrocortisone alone, but substrate induction could be demonstrated only if these animals were treated at the same time with hydrocortisone.