Methylmalonyl-CoA is a biochemical compound that plays a crucial role in the metabolism of certain amino acids and fatty acids. It is formed from the breakdown of valine, isoleucine, threonine, and methionine, as well as from the metabolism of odd-chain fatty acids. In the body, methylmalonyl-CoA is converted into succinyl-CoA through the action of the enzyme methylmalonyl-CoA mutase. This conversion is important for energy production and the synthesis of various biomolecules. Deficiencies in the enzymes involved in this process can lead to metabolic disorders.