Coenzyme A metabolism.
The metabolism of coenzyme A and control of its synthesis are reviewed. Pantothenate kinase is an important rate-controlling enzyme in the synthetic pathway of all tissues studied and appears to catalyze the flux-generating reaction of the pathway in cardiac muscle. This enzyme is strongly inhibited by coenzyme A and all of its acyl esters. The cytosolic concentrations of coenzyme A and acetyl coenzyme A in both liver and heart are high enough to totally inhibit pantothenate kinase under all conditions. Free carnitine, but not acetyl carnitine, deinhibits the coenzyme A-inhibited enzyme. Carnitine alone does not increase enzyme activity. Thus changes in the acetyl carnitine-to-carnitine ratio that occur with nutritional states provides a mechanism for regulation of coenzyme A synthetic rates. Changes in the rate of coenzyme A synthesis in liver and heart occurs with fasting, refeeding, and diabetes and in heart muscle with hypertrophy. The pathway and regulation of coenzyme A degradation are not understood.
Robishaw
J D
JD
Neely
J R
JR
D000105:Acetyl Coenzyme A / Q000378:metabolism; D000818:Animals; D003065:Coenzyme A / Q000096:biosynthesis / Q000378:metabolism*; D004032:Diet; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010205:Pantothenic Acid / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor); D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
D010205:Pantothenic Acid; D000105:Acetyl Coenzyme A; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C023088:pantothenate kinase; D003065:Coenzyme A