Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Food intake, plasma and brain amino acid concentrations, liver amino acid catabolic enzyme activities, and whole-brain neurotransmitter and metabolite concentrations were measured in young rats adapted for 11 d to diets containing from 5 to 75% (in increments of 5%) casein. Food intake was depressed initially in rats fed diets containing 5, 10% or greater than 35% casein. For the duration of the experiment, food intakes of the groups fed the higher protein diets improved on successive days; the length and severity of the depression were proportional to the protein content of the diet fed. Rats fed low levels of protein grew poorly, and their food intake remained depressed. The gradual improvement in growth and food intake of rats fed diets containing more than 35% casein was accompanied by dramatic increases in the activities of serine-threonine dehydratase (SDH, EC 4.2.1.16) and glutamate-pyruvate aminotransferase (GPT, EC 2.6.1.1) in liver. The increase in amino acid catabolic activity was accompanied by decreases in the concentrations of most amino acids in plasma and brain. However, concentrations of branched-chain amino acids, in both plasma and brain, increased in direct proportion to the protein concentration of the diet fed. As a result of these reciprocal responses, the total concentration of indispensable amino acids in brain (IAA) was maintained within a narrow range of values, despite a sixfold range of protein intakes. Whole-brain concentrations of norepinephrine, dopamine and serotonin were not correlated with dietary protein concentration, total food intake or protein intake. Brain concentrations of homovanillic acid and 5-hydroxyindoleacetic acid were correlated inversely with protein intake and that of 3,4-dihydroxyphenylacetic acid was correlated directly with food intake. Protein intake appeared to be related to the animal's ability to maintain brain total IAA content between some upper and lower limits. Our results indicate that this was accomplished initially through downward adjustment of protein intake and subsequently through an increase in catabolic capacity for the amino acids.
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PMID:Adaptation of rats to diets containing different levels of protein: effects on food intake, plasma and brain amino acid concentrations and brain neurotransmitter metabolism. 285 80

We studied the effect of carbamoylphosphate (CP) on L-aspartate aminotransferase (GOT) and L-alanine aminotransferase (GPT), compared to its effect on L-threonine deaminase (TD). GPT and GOT were slightly inhibited by CP, while TD was strongly inhibited. GPT and TD, but not GOT, were inactivated when preincubated with CP. Only GOT was enhanced by pyridoxal 5'-phosphate (PLP), but not when the coenzyme was preincubated with CP. When the enzymes were resolved by p-chloromercuribenzoate (PCMB) treatment to apoenzymes, only GOT retained 47% of the original activity. Reconstitution of the apoenzymes with PLP also followed different course; activities of GPT and TD were completely restored while GOT remained partially inactivated. Treatment of apoenzymes with CP resulted in impairment of their reconstitution except GPT, activity of which could be completely restored. When PLP was pre-treated with CP before reconstitution, however, even GPT was only partially restored. The data indicated that CP affect activities of these enzymes at different levels, holoenzymes, PLP and probably apoenzymes. Under a concentration of PLP, activity of GOT would be most enhanced, followed by TD then GPT. In the presence of CP, this effect would be eliminated.
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PMID:The regulation of aminotransferase activity by carbamoyl-phosphate. 812 Dec 41