The activity of phosphoenolpyruvate carboxykinase in rat tissues. Assay techniques and effects of dietary and hormonal changes.
1. Phosphoenolpyruvate carboxykinase was assayed by three methods: (i) incorporation of H(14)CO(3) (-) into oxaloacetate: (ii) conversion of oxaloacetate into phosphoenolpyruvate, subsequently assayed enzymically; and (iii) transfer of (32)P from [gamma-(32)P]GTP to oxaloacetate. 2. Enzyme activity is increased in liver and epididymal adipose tissue in alloxan-diabetes and starvation, and in kidney in starved, acidotic and steroid-treated animals. 3. The ratios of the ;back' to the ;forward' reactions in liver, kidney and epididymal adipose tissue are different and characteristic of each tissue; they differ markedly from values reported for the purified mitochondrial enzyme. 4. The ratio of the ;back' to ;forward' reaction in any one tissue is constant in adrenalectomized, diabetic, acidotic and steroid-treated animals. 5. In starved animals, the ratio is increased in liver and kidney, but decreased in epididymal adipose tissue. 6. Administration of l-tryptophan results in an acute (1h) increase in activity measured in the ;forward' direction alone in liver and epididymal adipose tissue, but not in kidney.
D000273:Adipose Tissue / Q000201:enzymology; D000315:Adrenalectomy; D000643:Ammonium Chloride; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000378:metabolism*; D051381:Rats; D013217:Starvation / Q000201:enzymology; D014221:Triamcinolone / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology
D000643:Ammonium Chloride; D014221:Triamcinolone; D014364:Tryptophan; D010729:Phosphoenolpyruvate Carboxykinase (GTP)