Tryptophan pyrrolase in haem regulation. The mechanism of the opposite effects of tryptophan on rat liver 5-aminolaevulinate synthase activity and the haem saturation of tryptophan pyrrolase

Tryptophan pyrrolase in haem regulation

1. Rat liver tryptophan pyrrolase activity is enhanced by a hormonal-type mechanism during the first 2 days of starvation and by a substrate-type mechanism during the subsequent 2 days. 5-Aminolaevulinate synthase activity is also enhanced during the first 2 days of starvation, but returns thereafter to values resembling those observed in the fed rat. Treatments that prevent or reverse the enha...

Tryptophan Pyrrolase and 8-Aminolaevulinate Synthase: EVIDENCE FOR AN ENDOGENOUS REGULATORY HAEM FRACTION IN RAT LIVER

Tryptophan and tryptophan pyrrolase in haem regulation. The role of lipolysis and direct displacement of serum-protein-bound tryptophan in the opposite effects of administration of endotoxin, morphine, palmitate, salicylate and theophylline on rat liver 5-aminolaevulinate synthase activity and the haem saturation of tryptophan pyrrolase.

1. The increase in the haem saturation of rat liver tryptophan pyrrolase caused by tryptophan administration was previously shown to be associated with a decrease in 5-aminolaevulinate synthase activity. 2. It is now shown that similar reciprocal effects are caused by palmitate and salicylate, both of which increase tryptophan availability to the liver by direct displacement of the serum-protei...

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...