Fatty acid beta-oxidation in glyoxysomes. Characterization of a new tetrafunctional protein (MFP III).

We describe a new form of a multifunctional protein possessing the enzyme activities of delta 3, delta 2-enoyl-CoA isomerase, 3-hydroxyacyl-CoA epimerase, L-3-hydroxyacyl-CoA dehydrogenase and L-3-hydroxyacyl-CoA forming 2-trans-enoyl-CoA hydratase. This isoform, characterized by a molecular mass of 81 kDa and an isoelectric point above pH 9, was designated MFP III. Along with the tetrafunctional 76.5 kDa MFP II and the trifunctional 74 kDa MFP I, MFP III participates in degradation of fatty acid in glyoxysomes during mobilization of fat reserves. In combination with thiolase, MFP III encompasses all activities to degrade 3-cis-enoyl-CoAs to acetyl-CoA.