Defining a direction: Electron transfer and catalysis in Escherichia coli complex II enzymes

Elena Maklashina, Gary Cecchini, Sergei A. Dikanov

Research output: Contribution to journalReview articlepeer-review


There are two homologous membrane-bound enzymes in Escherichia coli that catalyze reversible conversion between succinate/fumarate and quinone/quinol. Succinate:ubiquinone reductase (SQR) is a component of aerobic respiratory chains, whereas quinol:fumarate reductase (QFR) utilizes menaquinol to reduce fumarate in a final step of anaerobic respiration. Although, both protein complexes are capable of supporting bacterial growth on either minimal succinate or fumarate media, the enzymes are more proficient in their physiological directions. Here we evaluate factors that may underlie this catalytic bias. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.

Original languageEnglish (US)
Pages (from-to)668-678
Number of pages11
JournalBiochimica et Biophysica Acta - Bioenergetics
Issue number5
StatePublished - May 2013
Externally publishedYes


  • Complex II
  • Iron sulfur cluster
  • Protein electron transport
  • Quinol:fumarate reductase
  • Quinone binding site
  • Succinate:quinone oxidoreductase

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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