Tryptophan Pyrrolase of Liver

Tryptophan pyrrolase, measured in an assay where its activity was proportional to its reaction with a specific antiserum, was induced in the liver of adrenalectomized rats by only those tryptophan analogues that also specifically promoted the conjugation of the apotryptophan pyrrolase in vitro and in vivo whether or not these analogues had affinity for the catalytic site of the tryptophan pyrrolase. The apotryptophan pyrrolase induced by hydrocortisone became conjugated upon injection of these analogues, and the elevated level was maintained in vivo as long as sufficient amount of the analogues was present. This action in vivo of the inducers with a site on the enzyme different from the catalytic site was associated with a decreased rate of disappearance of the protein and an increased rate of its synthesis.