Acylcarnitine C3 Unit Converter

Acylcarnitine C3, also called propionylcarnitine, is a short-chain acylcarnitine formed when a propionyl group from propionyl-CoA is transferred to L-carnitine. It plays a key role in transporting propionyl groups out of mitochondria and into the bloodstream for disposal.

Propionyl-CoA is produced during the breakdown of certain amino acids (isoleucine, valine, threonine, methionine), odd-chain fatty acids, and the side chain of cholesterol. Normally, propionyl-CoA is quickly converted to methylmalonyl-CoA and then succinyl-CoA for use in the citric acid cycle.

When this conversion is impaired, propionyl-CoA accumulates and is diverted to propionylcarnitine. Elevated C3 therefore reflects a bottleneck in propionate metabolism, which may point to enzyme deficiencies, vitamin B12 deficiency, or other metabolic disruptions.

Propionylcarnitine is produced in mitochondria throughout the body when propionyl-CoA is conjugated with L-carnitine by the enzyme carnitine acetyltransferase. Propionyl-CoA itself arises from the catabolism of branched-chain amino acids (isoleucine, valine), methionine, threonine, odd-chain fatty acids, cholesterol side chains, and from propionate produced by gut bacteria.