Influence of dietary nitrogen intake on mammalian branched chain alpha-keto acid dehydrogenase activity.
Male albino rats (100-130 g) were fed diets of varying casein contents for a period of six days. Increasing the casein content from 0.38% to 22% led to an elevation of hepatic branched chain alpha-keto acid dehydrogenase (BCKAD) activity. Km values measured with alpha-ketoisocaproate and alpha-ketoisovalerate as substrates were not influenced by the dietary treatment. Replacing the casein content (22%) of the diet by an equivalent amount of amino acids resulted in a significant decrease in hepatic BCKAD activity. The decrease in Vmax values was not accompanied by changes in Km-values. No enhancement of hepatic enzyme activity was observed when increasing the amino acid content of the diet from 17.5% to 25%. Changes in enzyme activity due to alterations of the dietary nitrogen source were not observed in kidney and brain.
D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D000596:Amino Acids / Q000008:administration & dosage; D000818:Animals; D002364:Caseins / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage*; D045782:Hemiterpenes; D007651:Keto Acids / Q000378:metabolism; D007658:Ketone Oxidoreductases / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism*; D009584:Nitrogen / Q000008:administration & dosage*; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D002364:Caseins; D004044:Dietary Proteins; D045782:Hemiterpenes; D007651:Keto Acids; D009097:Multienzyme Complexes; C001505:alpha-ketoisovalerate; C013082:alpha-ketoisocaproic acid; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D009584:Nitrogen