Histidine Uptake and Histidine-degrading Enzymes
in Rat Tissues

Mk, Sahib; Cr, Murti

doi:10.1159/000458362

Cited by 3 publications

(2 citation statements)

References 7 publications

(7 reference statements)

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“…The depletion of body reserve protein as a consequence of protein malnutrition results in disturbances in protein metabolism and as a consequence excess of amino acids are excreted in urine. The basal activities of xanthine oxidase (Rowe & Wyngaarden, 1966), histidase and urocanase (Sahib Krishna Murti, 1969;Schirmer & Harper, 1970), arginase (Schimke, 1964), alanine aminotransferase (Rosen et al, 1959) and other functional enzymes are known to be significantly decreased in protein deficiency. In contrast, the basal activity of tyrosine aminotransferase appears to increase significantly.…”

Section: Discussionmentioning

confidence: 99%

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

Mukhtar

Sahib

Murti

1973

Biochemical Journal

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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 ofthis 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 abovementioned effects on the induction of hepatic tyrosine aminotransferase were reversed.In adult rats, depletion of available protein by feeding a 5% lactalbumin diet for 7 days leads to decreased rates of oxidation of tyrosine and phydroxyphenylpyruvate but not that of homogentisic acid (Al-Nejjar & Litwack, 1961). These authors found that decreased rates of oxidation of L-tyrosine and p-hydroxyphenylpyruvate correlated with a decrease in the activities of tyrosine aminotransferase and p-hydroxyphenylpyruvate oxidase. Also, the induction of tyrosine aminotransferase by Ltyrosine or by cortisol depends on the amount of protein ingested by the animal. By contrast, starvation for 48h causes the hepatic tyrosine aminotransferase activity to rise 100% above the basal value in 4-weekold intact and adrenalectomized rats fed on a 7 %

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Section: Discussionmentioning

confidence: 99%