Propionic acid is first converted to propionyl coenzyme A (propionyl-CoA), however, it directly enter either beta oxidation or the citric acid cycles. As propionic acid has three carbons, propionyl-CoA. In the majority of vertebrates, propionyl-CoA is carboxylated to D-methylmalonyl-CoA, which is then isomerised to L-methylmalonyl-CoA. A vitamin B12-dependent enzyme catalyzes rearrangement of L-methylmalonyl-CoA to succinyl-CoA, which can then be used as a substrate in the citric acid cycle.
Propionate is formed as the terminal three-carbon fragment (as propionyl-coenzyme A) in the oxidation of odd-number carbon fatty acids and from oxidation of the side chain of cholesterol. Radioactivity from propionate admin to fasting rats may appear in glycogen, glucose, citric acid cycle intermediates, amino acids, and proteins. The route of metabolism of propionic acid involves interaction with coenzyme A, carboxylation to form methylmalonyl-coenzyme A, and conversion to succinic acid, which enters the citric acid cycle. Propionic acid may be oxidized without forming ketone bodies and in contrast to acetic acid, is incorporated into a carbohydrate as well as lipid.
Bingham, E.; Cohrssen, B.; Powell, C.H.; Patty’s Toxicology Volumes 1-9 5th ed. John Wiley & Sons. New York, N.Y. (2001)., p. 5:706
The metab of radiolabeled sodium propionate was studied in rats three days after a single oral admin. Among the liver extracts, 89% of the liver radioactivity was found in trichloroacetic acid precipitated fraction, and 10% in glycogen.
KOZUKA H ET AL; EISEI KAGAKU 27 (5): 303-8 (1981)
Treatment with L-carnitine greatly enhanced the formation and excretion of short-chain acylcarnitines in three patients with propionic acidemia and in three normal controls. Mass spectrometry … identified the acylcarnitine as propionylcarnitine in patients with propionic acidemia. The normal children excreted mostly acetylcarnitine. Propionic acidemia and other organic acidurias are characterized by the intramitochondrial accumulation of short-chain acyl-Coenzyme A (CoA) compounds. The substrate specificity of the carnitine acetyltransferase enzyme and its steady state nature appears to facilitate elimination of propionyl groups while restoring the acyl-acyl-Coenzyme A:free acyl-CoenzymeA ratio in the mitochondrion. L-carnitine may be a useful therapeutic approach for elimination of toxic acyl acyl-Coenzyme A compounds in several of these disorders.
PMID:6725560 Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC437091 Roe CR et al; J Clin Invest 73 (6): 1785-8 (1984)
Propionic acid (10 mM) inhibited hepatocyte oxidation of 1-(14)C-pyruvate (10 mM) by 60%. This inhibition was not the result of substrate competition, as butyric acid had minimal effects on pyruvate oxidation. … Propionic acid also inhibited oxidation of 1-(14)C palmitic acid (0.8 mM) by hepatocytes isolated from fed rats. … These results demonstrate that propionic acid interferes with oxidative metabolism in intact hepatocytes.
PMID:3790065 Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1146796 Brass EP et al; Biochem J 236 (1): 131-6 (1986)
For more Metabolism/Metabolites (Complete) data for PROPIONIC ACID (7 total), please visit the HSDB record page.