A tungsten-containing active formylmethanofuran dehydrogenase in the thermophilic archaeon Methanobacterium wolfei

Eur J Biochem. 1992 Jul 15;207(2):559-65. doi: 10.1111/j.1432-1033.1992.tb17082.x.

Abstract

Methanobacterium wolfei is a thermophilic methanogenic archaeon which requires tungsten or molybdenum for growth. We have found that the organism contains two formylmethanofuran dehydrogenases, one of which is a tungsten enzyme. Indirect evidence indicates that the other formylmethanofuran dehydrogenase is a molybdenum enzyme. The tungsten enzyme was purified and characterized. The native enzyme had an apparent molecular mass of 130 kDa. SDS/PAGE revealed a composition of three subunits of apparent molecular mass 35, 51 and 64 kDa, the N-terminal amino acid sequences of two of which were determined. 0.3-0.4 mol tungsten/mol enzyme was found but no molybdenum. The pterin cofactor was identified as molybdopterin guanine dinucleotide. The purified enzyme exhibited a specific activity of 8.3 mumol.min-1.mg protein-1 and an apparent Km for formylmethanofuran and methylviologen of 13 microM and 0.4 mM, respectively. The optimum temperature for activity was 65 degrees C. At 40-60 degrees C, the rate increased with a Q10 of 1.9; the activation energy of the reaction was 45 kJ/mol. The enzyme was found to require potassium ions for thermostability. The oxygen-sensitive enzyme was not inactivated by cyanide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehyde Oxidoreductases / chemistry*
  • Aldehyde Oxidoreductases / metabolism
  • Amino Acid Sequence
  • Catalysis
  • Hot Temperature
  • Iron / metabolism
  • Kinetics
  • Methanobacterium / enzymology*
  • Molecular Sequence Data
  • Molecular Weight
  • Molybdenum / metabolism
  • Peptide Fragments / chemistry
  • Potassium Chloride / pharmacology
  • Protein Denaturation / drug effects
  • Spectrum Analysis
  • Tungsten / metabolism*

Substances

  • Peptide Fragments
  • Potassium Chloride
  • Molybdenum
  • Iron
  • Aldehyde Oxidoreductases
  • formylmethanofuran dehydrogenase
  • Tungsten