These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Physiological role of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein.
    Author: Jiang LL, Kurosawa T, Sato M, Suzuki Y, Hashimoto T.
    Journal: J Biochem; 1997 Mar; 121(3):506-13. PubMed ID: 9133619.
    Abstract:
    The second and third reactions of the peroxisomal beta-oxidation spiral are thought to be catalyzed by enoyl-CoA hydratase/L-3-hydroxyacyl-CoA dehydrogenase bifunctional protein (L-bifunctional protein). Recently, we found the presence of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein (D-bifunctional protein) in mammalian peroxisomes. Therefore, we studied the physiological role of the D-bifunctional protein. The contents of the L- and D-bifunctional proteins were about 0.01 and 0.5 microg/mg protein, respectively, in cultured human skin fibroblasts. The activity of conversion of hexadecenoyl-CoA to 3-ketopalmitoyl-CoA by the D-bifunctional protein was estimated to be about 0.5 milliunit/mg of fibroblast protein. This value was about 100-fold that of the L-bifunctional protein in the fibroblasts. From comparison of the activities of the bifunctional proteins with the rate of palmitate oxidation and the activities of acyl-CoA oxidase and 3-ketoacyl-CoA thiolase, it is proposed that the D-bifunctional protein plays a major role in the peroxisomal oxidation of palmitate in the fibroblasts. The contents of both the L- and D-bifunctional proteins in liver were about 2.5 microg/mg protein. Therefore, it is suggested that the D-bifunctional protein also plays a significant role in human liver peroxisomal fatty acid oxidation. Actions of the bifunctional proteins on enoyl forms of other acyl-CoA derivatives were examined. The D-bifunctional protein but not the L-bifunctional protein reacted with 2-methylhexadecenoyl-CoA and 3alpha,7alpha,12alpha-trihydroxy-5beta-cholest-2 4-enoyl-CoA. We propose that, among the reactions of the distinct group of carboxylates oxidized specifically in peroxisomes, oxidation of 2-methyl-branched fatty acids and side-chain shortening of cholesterol for bile acid formation are catalyzed by the D-bifunctional protein, but not the L-bifunctional protein.
    [Abstract] [Full Text] [Related] [New Search]