Comparison of ligand polarization and enzyme activation in medium- and short-chain acyl-coenzyme A dehydrogenase-novel analog complexes

Teresa R. Lamm, Theresa D. Kohls, Amy K Saenger, Marian T. Stankovich

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Spectroelectrochemical and off-resonance Raman indicate that substrate/product binding to medium-chain acyl-coenzyme A (CoA) dehydrogenase (pMCAD) results in ligand polarization and positive flavin potential shifts, which activate the enzyme for electron transfer. Bacterial short-chain acyl-CoA dehydrogenase (bSCAD) typically exhibits smaller potential shifts upon substrate/product binding that have not been linked to ligand polarization. To further investigate the roles of ligand binding and polarization in activation, several novel aromatic carboxyloyl-CoAs were designed. These analogs allowed for the first direct comparison of pMCAD and bSCAD mechanisms. The results indicate that pMCAD activation can occur without perceptible analog polarization. bSCAD data provide the first spectral evidence of ligand polarization. The potential alterations exhibited by ligand-bound bSCAD are smaller than those of pMCAD, while their directionality and magnitude suggest differing enzyme-analog interactions. Such data provide the first indication of variations in the activation mechanism of these enzymes, which were thought to be comparable in both structure and function.

Original languageEnglish (US)
Pages (from-to)251-261
Number of pages11
JournalArchives of Biochemistry and Biophysics
Volume409
Issue number2
DOIs
StatePublished - Jan 15 2003

Keywords

  • ACD
  • Activation
  • Carboxyloyl-CoA
  • Formal potential
  • MCAD
  • Midpoint potential
  • Polarization
  • SCAD
  • Spectroelectrochemistry
  • Thermodynamic

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