The source of malonyl-CoA in rat heart. The calcium paradox releases acetyl-CoA carboxylase and not propionyl-CoA carboxylase.
The formation of malonyl-CoA in rat heart is catalyzed by cytosolic acetyl-CoA carboxylase. The existence of this enzyme in heart is difficult to prove by the abundant occurrence of mitochondrial propionyl-CoA carboxylase, which is also able to catalyze the carboxylation of acetyl-CoA. We used the calcium paradox as a tool to separate cytosolic components from the remaining heart, and found that acetyl-CoA carboxylase activity was preferentially released, like lactate dehydrogenase and carnitine, while propionyl-CoA carboxylase was almost fully retained. Acetyl-CoA carboxylase activity was determined after activation by citrate ion and Mg2+. The activity decreased to 64% by 48 h of fasting.
Scholte
H R
HR
Luyt-Houwen
I E
IE
Dubelaar
M L
ML
Hulsmann
W C
WC
D000103:Acetyl-CoA Carboxylase / Q000032:analysis*; D000214:Acyl Coenzyme A / Q000096:biosynthesis*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000032:analysis*; D002331:Carnitine / Q000032:analysis; D002334:Carnitine O-Palmitoyltransferase / Q000032:analysis; D008025:Ligases / Q000032:analysis*; D008297:Male; D008316:Malonyl Coenzyme A / Q000096:biosynthesis*; D043586:Methylmalonyl-CoA Decarboxylase; D009206:Myocardium / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains
D000214:Acyl Coenzyme A; D008316:Malonyl Coenzyme A; D002334:Carnitine O-Palmitoyltransferase; D002262:Carboxy-Lyases; D008025:Ligases; D000103:Acetyl-CoA Carboxylase; D043586:Methylmalonyl-CoA Decarboxylase; D002331:Carnitine; D002118:Calcium