Bifunctional Protein

Recent studies from different laboratories have led to the identification of a new peroxisomal multifunctional P-oxidation protein with both enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase activity. This protein was first identified by Adamski and coworkers18 in a systematic study to identify 17P-hydroxysteroiddehydrogenases. The enzyme turned out to be localized in peroxisomes.19 Subsequent cloning of the cDNA led to the surprising discovery that the encoded protein appeared to have 3 domains, including an enoyl-CoA hydratase, 3-OH-acyl-CoA dehydrogenase and sterol-carrier-protein domain. Studies by Leenders et al.20.established that the 78 kDa protein indeed catalyzes all 3 partial reactions.

Independent studies from several laboratories also led to the identification of this enzyme. - In 1994 Novikov et al. had already found that peroxisomes contain multiple 3-hydroxyacyl-CoA dehydrogenases of which one turned out to be the newly recognized D-bifunctional protein.21,2 Systematic studies by the group of Hiltunen25,26 into the various enoyl-CoA hydratases in rat liver, and the group of Hashimoto23'24 also led to the identification of this multifunctional protein which has different names including multifunctional protein 2 (MFP 2),21,22 multifunctional enzyme II (MFE II)25,26 and D-bifunctional protein.23,24 A problem with the names multifunctional enzyme or multifunctional protein is that there are many multifunctional enzymes including a mitochondrial multifunctional enzyme involved in P-oxidation.28 In order to avoid this confusion, we have suggested the name peroxisomal multifunctional P-oxidation protein 2 (pMOP 2).29

However, until there is a unified nomenclature we will use the term D-bifunctional

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