The mechanism of inhibition of rat liver tryptophan pyrrolase activity by 4-hydroxypyrazolo[3,4-d]pyrimidine (allopurinol)

Tryptophan catabolism by tryptophan pyrrolase in rat liver. The effect of tryptophan loads and changes in tryptophan pyrrolase activity.

We investigated how changes in tryptophan pyrrolase activity and tryptophan loads affect the breakdown of tryptophan was estimated by injecting rats with [ring-2-14-C]tryptophan and measuring respiratory 14-CO2. We concluded, contrary to previous reports, that induction of tryptophan pyrrolase definitely will increase the rate of tryptophan breakdown. Tryptophan loads also increase tryptophan b...

Tryptophan Catabolism by Tryptophan Pyrrolase in Rat Liver THE EFFECT OF TRYPTOPHAK LOADS AKD CHAKGES IN TRYPTOPHAN PYRROLASE ACTIVITY*

We investigated how changes in tryptophan pyrrolase activity and tryptophan loads affect the breakdown of tryptophan by tryptophan pyrrolase. Breakdown of tryptophan was estimated by injecting rats with [ring-ZJ%]tryptophan and measuring respiratory 14C02. We concluded, contrary to previous reports, that induction of tryptophan pyrrolase definitely will increase the rate of tryptophan breakdown...

Determination of tryptophan pyrrolase activity in rat liver homogenates.

A microsomal iron-porphyrin activator of rat liver tryptophan pyrrolase.

Tryptophan pyrrolase, the enzyme that catalyzes the oxidation of tryptophan to formylkynurenine, has been localized in the 11,000 X g supernatant fraction of mammalian liver homogenates (l), which contains microsomes and cell sap. In the course of the present investigations (Z), it was observed that the isolated microsomal fraction of rat liver is devoid of this enzyme. However, addition of thi...

The effects of chemical porphyrogens and drugs on the activity of rat liver tryptophan pyrrolase.

1. Drugs such as phenobarbitone and phenylbutazone, which increase the concentration of microsomal haem and cytochrome P-450, also increase the saturation of rat liver apo-(tryptophan pyrrolase) with its haem activator, as does the haem precursor 5-aminolaevulinate. 2. At 4h after the administration of the porphyrogens 2-allyl-2-isopropylacetamide, 3,5-diethoxycarbonyl-1,4-dihydrocollidine and ...