Subcellular distribution and characteristics of ciprofibroyl-CoA synthetase in rat liver. Its possible identity with long-chain acyl-CoA synthetase.
The subcellular distribution and characteristics of ciprofibroyl-CoA synthetase were studied in rat liver and compared with those of long-chain acyl-CoA synthetase (palmitate as substrate) which, as already known, is distributed among mitochondria, microsomes and peroxisomes. Upon differential centrifugation, the subcellular distribution of ciprofibroyl-CoA synthetase followed closely that of palmitoyl-CoA synthetase and was specifically inactivated in the mitochondrial fraction by freezing and thawing, a behaviour already described for palmitoyl-CoA synthetase. Both enzyme activities were found to co-purify through several steps from rat liver microsomes. By using a partially purified enzyme, the activation of ciprofibrate to its acyl-CoA ester followed Michaelis-Menten kinetics with an apparent Km of 0.63 +/- 0.1 mM. Ciprofibroyl-CoA synthetase was competitively inhibited by 25 and 50 microM-palmitic acid. Higher concentrations of the fatty acid resulted in a mixed type of inhibition. Conversely, ciprofibrate up to 0.5 mM was found to inhibit competitively palmitoyl-CoA synthetase, whereas higher concentrations also resulted in a mixed inhibition. The highest activity of ciprofibroyl-CoA synthetase was found in fat and liver homogenates. The distribution of the enzyme in different rat tissues was similar to that of palmitoyl-CoA synthetase. The present results suggest that long-chain acyl-CoA synthetase and ciprofibroyl-CoA synthetase activities reside in identical or closely related proteins.
Amigo
L
L
Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago.
McElroy
M C
MC
Morales
M N
MN
Bronfman
M
M
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002995:Clofibric Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D003066:Coenzyme A Ligases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D013347:Subcellular Fractions / Q000201:enzymology; D014018:Tissue Distribution; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
D000214:Acyl Coenzyme A; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C051514:ciprofibrate-coenzyme A; D002995:Clofibric Acid; D003066:Coenzyme A Ligases; C090799:FAA2 protein, S cerevisiae; D000098859:Long-Chain-Fatty-Acid-CoA Ligase