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: Effect of transition-state analogues on the redox properties of medium-chain acyl-CoA dehydrogenase.
    Author: Johnson BD, Mancini-Samuelson GJ, Stankovich MT.
    Journal: Biochemistry; 1995 May 30; 34(21):7047-55. PubMed ID: 7766614.
    Abstract:
    The binding of substrate/product or transition-state intermediates modifies the properties of medium-chain fatty acyl-CoA dehydrogenase (MCAD) by causing the redox potential to shift positive and the oxygen reactivity to slow by 3000-fold. Two ligands, identified as being the most effective in slowing oxygen reactivity, were 2-azaoctanoyl-CoA and 3-thiaoctanoyl-CoA [Wang, R., & Thorpe, C. (1991) Biochemistry 30, 7895-7901]. We have measured the potential shifts caused by the binding of both ligands to determine which is most similar to the potential shift caused by substrate/product mixture, the assumption being that the best transition-state structural intermediate would give the potential shift most similar to that of substrate/product [Lenn, N.D., Stankovich, M.T., & Liu, H. (1990) Biochemistry 29, 10594-10602]. Both ligands shifted the potential positive, but the shift caused by 2-azaoctanoyl-CoA was 65% that of substrate/product, while 3-thiaoctanoyl-CoA was only 20% of that value. This positive shift is proposed to be caused by a resonance form stabilized by the interaction of the catalytically essential carbonyl of the acyl-CoA with two hydrogen bonds from the enzyme, which induces a partial negative charge on the carbonyl and a partial positive charge on carbon 2 of the ligand and carbon 3 of the substrate/product couple. The X-ray structure shows that carbons 2 and 3 of the substrate/product overlap the diazadiene portion of the flavin ring [Kim, J.-J. P., Wang, M., & Paschke, R. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 7523-7527].(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]