Carnitine palmitoyltransferase in liver and five extrahepatic tissues in the rat. Inhibition by DL-2-bromopalmitoyl-CoA and effect of hypothyroidism.
Mitochondria were isolated from rat adult liver, foetal liver, kidney cortex, heart, skeletal muscle and interscapular brown adipose tissue. DL-2-Bromopalmitoyl-CoA inhibited the overt form of carnitine palmitoyltransferase (CPT1) in heart, skeletal muscle and brown adipose tissue, with an IC50 value (concentration giving 50% inhibition) of 1.3-1.6 microM. By contrast, the IC50 value for inhibition of the kidney or adult liver enzyme was 0.08-0.1 microM. CPT1 in near-term foetal liver differed from that in adult liver in that the IC50 for inhibition by 2-bromopalmitoyl-CoA was 0.57 microM. It is suggested that there may be tissue-specific forms of the catalytic entity of CPT1 and that foetal liver may contain a mixture of adult liver- and muscle-type enzymes. In rats made hypothyroid by administration of propylthiouracil and an iodine-deficient diet, hepatic CPT1 activity was decreased by 83%. However, CPT1 activity in extrahepatic tissues showed no adaptive decrease in hypothyroidism.
D000214:Acyl Coenzyme A / Q000031:analogs & derivatives*; D000217:Acyltransferases / Q000378:metabolism*; D000273:Adipose Tissue / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002950:Citrate (si)-Synthase / Q000378:metabolism; D007037:Hypothyroidism / Q000201:enzymology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008928:Mitochondria / Q000201:enzymology; D009132:Muscles / Q000201:enzymology / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
C046844:2-bromopalmitoyl coenzyme A; D000214:Acyl Coenzyme A; D010171:Palmitoyl Coenzyme A; D000217:Acyltransferases; D002334:Carnitine O-Palmitoyltransferase; D002950:Citrate (si)-Synthase