Characterisation of a novel enzyme of human fatty acid beta-oxidation: a matrix-associated, mitochondrial 2-enoyl-CoA hydratase.

We present evidence for the existence of a previously unrecognised enzyme of mitochondrial beta-oxidation in man. This enzyme, which is situated in the mitochondrial matrix and has medium- and long-chain 2-enoyl-CoA hydratase activity, was identified by studying tissues from a patient with a severe deficiency of the trifunctional protein of mitochondrial beta-oxidation. The novel enzyme is present in all tissues studied--heart, liver and cultured skin fibroblasts--but is particularly active in liver. Together with other recently identified enzymes of mitochondrial beta-oxidation, the existence of this new enzyme suggests that two mitochondrial beta-oxidation enzyme systems exist in man: one associated with the mitochondrial membrane, responsible for the beta-oxidation of long-chain fatty acids and one in the mitochondrial matrix, responsible for the oxidation of medium- and short-chain fatty acids.