CARBON-BY-CARBON DISCRIMINATION OF C-13 INCORPORATION INTO LIVER FATTY-ACIDS

Quantitative carbon-by-carbon analysis would be useful in determining the origin and fate of carbons involved in fatty acid metabolism. Incorporation of C-13 from 2-[C-13]acetate into specific carbons of liver fatty acids was lowest at the n-2 carbon of saturates and monoenes but was 47% greater at acyl C1 than at C2, suggesting substantial redistribution of the C-13 from C2 to C1 of acetyl CoA or malonyl CoA prior to C-13 incorporation into fatty acids during de novo synthesis or during elongation. Thus, C-13 derived from exogenous acetate can be quantitatively measured and is differentially incorporated into individual carbons depending on position in the fatty acid molecule.