Metabolism of amino acids in protein-calorie-deficient rats.
The overall oxidative degradation of leucine and phenylalanine, measured in vivo in rats fed on a 2%-casein diet for 8 weeks, is markedly decreased as compared with controls, whereas that of glutamate and alanine is apparently unaffected. The decrease in leucine degradation is due, at least in part, to a block before the formation of 3-methylbutyryl-CoA (isovaleryl-CoA) in the catabolic pathway. This phenomenon is accompanied by increased incorporation of [(14)C]leucine into liver proteins, decreased urinary excretion of leucine and increased urinary excretion of 4-methyl-2-oxopentanoate (alpha-oxoisocaproate) by protein-depleted animals. The results suggest the existence of adaptive mechanisms that function to conserve an indispensable carbon skeleton.
D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002208:Caproates / Q000652:urine; D002247:Carbon Isotopes; D002364:Caseins; D003065:Coenzyme A / Q000378:metabolism; D003677:Deficiency Diseases / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism; D007930:Leucine / Q000378:metabolism / Q000652:urine; D008099:Liver / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism; D014176:Protein Biosynthesis; D011488:Protein Deficiency / Q000378:metabolism*; D051381:Rats; D014631:Valerates / Q000378:metabolism
D000596:Amino Acids; D002208:Caproates; D002247:Carbon Isotopes; D002364:Caseins; D005971:Glutamates; D014631:Valerates; D010649:Phenylalanine; D007930:Leucine; D000409:Alanine; D003065:Coenzyme A