Determination of malonyl-coenzyme A in rat heart, kidney, and liver: a comparison between acetyl-coenzyme A and butyryl-coenzyme A as fatty acid synthase primers in the assay procedure.

The malonyl-CoA assay was nonlinear at low malonyl-CoA concentrations when labeled acetyl-CoA was used as fatty acid synthase primer. Linearity was obtained with low concentrations of both fatty acid synthase and labeled acetyl-CoA, but then the assay was disturbed by the diluting effect of endogenous acetyl-CoA. The problems of nonlinearity and dilution of radioactivity by endogenous compounds were absent when labeled butyryl-CoA was used as primer. The levels of malonyl-CoA in rat heart, kidney, and liver were determined. The use of butyryl-CoA gave higher values of malonyl-CoA.