Si-face Stereospecificity at C5 of Coenzyme F420 for F420H2 Oxidase From Methanogenic Archaea as Determined by Mass Spectrometry

FEBS J. 2005 Oct;272(20):5337-42. doi: 10.1111/j.1742-4658.2005.04931.x.


Coenzyme F420 is a 5-deazaflavin. Upon reduction, 1,5 dihydro-coenzyme F420 is formed with a prochiral centre at C5. All the coenzyme F420-dependent enzymes investigated to date have been shown to be Si-face stereospecific with respect to C5 of the deazaflavin, despite most F420-dependent enzymes being unrelated phylogenetically. In this study, we report that the recently discovered F420H2 oxidase from methanogenic Archaea is also Si-face stereospecific. The enzyme was found to catalyse the oxidation of (5S)-[5-2H1]F420H2 with O2 to [5-1H]F420 rather than to [5-2H]F420 as determined by MALDI-TOF MS. (5S)-[5-2H1]F420H2 was generated by stereospecific enzymatic reduction of F420 with (14a-2H2)-[14a-2H2] methylenetetrahydromethanopterin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Euryarchaeota / enzymology*
  • Flavin Mononucleotide / chemistry
  • Molecular Structure
  • NADH, NADPH Oxidoreductases / chemistry*
  • Oxidation-Reduction
  • Oxidoreductases Acting on CH-NH Group Donors / chemistry
  • Pterins / chemistry
  • Riboflavin / analogs & derivatives*
  • Riboflavin / chemistry
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Stereoisomerism


  • N(5),N(10)-methylene-tetrahydromethanopterin
  • Pterins
  • 5-deaza-FMN
  • coenzyme F420
  • Flavin Mononucleotide
  • Oxidoreductases Acting on CH-NH Group Donors
  • methylenetetrahydromethanopterin dehydrogenase
  • NADH, NADPH Oxidoreductases
  • F420-dependent NADP reductase
  • Riboflavin