Effect of high- and low-protein diets on the regulation of rat liver tyrosine aminotransferase and tryptophan oxygenase activities by L-tyrosine and L-tryptophan.
Induction of rat liver tyrosine aminotransferase by l-tyrosine and tryptophan oxygenase by l-tryptophan was studied in groups of rats fed on diets containing 18 or 5% protein. The basal activity of hepatic tyrosine aminotransferase of rats receiving 5% protein gradually increased with the age of the animals but that of rats receiving 18% protein did not. l-Tyrosine induced hepatic tyrosine aminotransferase in rats receiving 18% protein when tested at ages from 4 to 20 weeks. When induction by l-tyrosine was carried out in rats receiving the 5% protein diet, significant induction of tyrosine aminotransferase occurred only in 4- or 6-week-old rats. Induction by l-tryptophan of tryptophan oxygenase in liver or the basal activity of this enzyme in liver did not differ between the groups fed on 5 and 18% protein. On changing the diet from 0 to 18% protein, the above-mentioned effects on the induction of hepatic tyrosine aminotransferase were reversed.
D000818:Animals; D001835:Body Weight; D004044:Dietary Proteins / Q000378:metabolism*; D004790:Enzyme Induction; D008099:Liver / Q000378:metabolism*; D008297:Male; D009929:Organ Size; D051381:Rats; D014364:Tryptophan / Q000494:pharmacology; D014366:Tryptophan Oxygenase / Q000378:metabolism*; D014443:Tyrosine / Q000494:pharmacology; D014444:Tyrosine Transaminase / Q000378:metabolism*
D004044:Dietary Proteins; D014443:Tyrosine; D014364:Tryptophan; D014366:Tryptophan Oxygenase; D014444:Tyrosine Transaminase