Publications

• Tungstate can substitute for molybdate in sustaining growth of Methanobacterium thermoautotrophicum. Identification and characterization of a tungsten isoenzyme of formylmethanofuran dehydrogenase.

  Bertram P.A., Schmitz R.A., Linder D., Thauer R.K.

  Methanobacterium thermoautotrophicum (strain Marburg) was found to grow on media supplemented with tungstate rather than with molybdate. The Archaeon then synthesized a tungsten iron-sulfur isoenzyme of formylmethanofuran dehydrogenase. The isoenzyme was purified to apparent homogeneity and shown ... >> More

  Methanobacterium thermoautotrophicum (strain Marburg) was found to grow on media supplemented with tungstate rather than with molybdate. The Archaeon then synthesized a tungsten iron-sulfur isoenzyme of formylmethanofuran dehydrogenase. The isoenzyme was purified to apparent homogeneity and shown to be composed of four different subunits of apparent molecular masses 65 kDa, 53 kDa, 31 kDa, and 15 kDa and to contain per mol 0.4 mol tungsten, < 0.05 mol molybdenum, 8 mol non-heme iron, 8 mol acid-labile sulfur and molybdopterin guanine dinucleotide. Its molecular and catalytic properties were significantly different from those of the molybdenum isoenzyme characterized previously. The two isoenzymes also differed in their metal specificity: the active molybdenum isoenzyme was only synthesized when molybdenum was available during growth whereas the active tungsten isoenzyme was also generated during growth of the cells on molybdate medium. Under the latter conditions the tungsten isoenzyme was synthesized containing molybdenum rather than tungsten. << Less

  Arch Microbiol 161:220-228(1994) [PubMed] [EuropePMC]

• The active species of 'CO2' utilized by formylmethanofuran dehydrogenase from methanogenic Archaea.

  Vorholt J.A., Thauer R.K.

  Formylmethanofuran dehydrogenase from methanogenic Archaea catalyzes the reversible conversion of CO2 and methanofuran to formylmethanofuran, which is an intermediate in methanogenesis from CO2, a biological process yielding approximately 0.3 billion tons of CH4 per year. With the enzyme from Meth ... >> More

  Formylmethanofuran dehydrogenase from methanogenic Archaea catalyzes the reversible conversion of CO2 and methanofuran to formylmethanofuran, which is an intermediate in methanogenesis from CO2, a biological process yielding approximately 0.3 billion tons of CH4 per year. With the enzyme from Methanosarcina barkeri, it is shown that CO2 rather than HCO3-is the active species of 'CO2' utilized by the dehydrogenase. Evidence is also presented that the enzyme catalyzes a methanofuran-dependent exchange between CO2 and the formyl group of formylmethanofuran. The results are consistent with N-carboxymethanofuran being an intermediate in CO2 reduction to formylmethanofuran. << Less

  Eur J Biochem 248:919-924(1997) [PubMed] [EuropePMC]

• Formylmethanofuran dehydrogenases from methanogenic Archaea. Substrate specificity, EPR properties and reversible inactivation by cyanide of the molybdenum or tungsten iron-sulfur proteins.

  Bertram P.A., Karrach M., Schmitz R.A., Boecher R., Albracht S.P.J., Thauer R.K.

  Formylmethanofuran dehydrogenases, which are found in methanogenic Archaea, are molybdenum or tungsten iron-sulfur proteins containing a pterin cofactor. We report here on differences in substrate specificity, EPR properties and susceptibility towards cyanide inactivation of the enzymes from Metha ... >> More

  Formylmethanofuran dehydrogenases, which are found in methanogenic Archaea, are molybdenum or tungsten iron-sulfur proteins containing a pterin cofactor. We report here on differences in substrate specificity, EPR properties and susceptibility towards cyanide inactivation of the enzymes from Methanosarcina barkeri, Methanobacterium thermoautotrophicum and Methanobacterium wolfei. The molybdenum enzyme from M. barkeri (relative activity with N-formylmethanofuran = 100%) was found to catalyze, albeit at considerably reduced apparent Vmax, the dehydrogenation of N-furfurylformamide (11%), N-methylformamide (0.2%), formamide (0.1%) and formate (1%). The molybdenum enzyme from M. wolfei could only use N-furfurylformamide (1%) and formate (3%) as pseudosubstrates. The molybdenum enzyme from M. thermoautotrophicum and the tungsten enzymes from M. thermoautotrophicum and M. wolfei were specific for N-formylmethanofuran. The molybdenum formylmethanofuran dehydrogenases exhibited at 77 K two rhombic EPR signals, designated FMDred and FMDox, both derived from Mo as shown by isotopic substitution with 97Mo. The FMDred signal was only displayed by the active enzyme in the reduced form and was lost upon enzyme oxidation; the FMDox signal was displayed by an inactive form and was not quenched by O2. The tungsten isoenzymes were EPR silent. The molybdenum formylmethanofuran dehydrogenases were found to be inactivated by cyanide whereas the tungsten isoenzymes, under the same conditions, were not inactivated. Inactivation was associated with a characteristic change in the molybdenum-derived EPR signal. Reactivation was possible in the presence of sulfide. << Less

  Eur. J. Biochem. 220:477-484(1994) [PubMed] [EuropePMC]

• The molybdoenzyme formylmethanofuran dehydrogenase from Methanosarcina barkeri contains a pterin cofactor.

  Karrasch M., Borner G., Enssle M., Thauer R.K.

  Recently formylmethanofuran dehydrogenase from the archaebacterium Methanosarcina barkeri has been shown to be a novel molybdo-iron-sulfur protein. We report here that the enzyme contains one mol of a bound pterin cofactor/mol molybdenum, similar but not identical to the molybdopterin of milk xant ... >> More

  Recently formylmethanofuran dehydrogenase from the archaebacterium Methanosarcina barkeri has been shown to be a novel molybdo-iron-sulfur protein. We report here that the enzyme contains one mol of a bound pterin cofactor/mol molybdenum, similar but not identical to the molybdopterin of milk xanthine oxidase. The two pterins, after oxidation with I2 at pH 2.5, showed identical fluorescence spectra and, after oxidation with permanganate at pH 13, yielded pterin 6-carboxylic acid. They differed, however, in their apparent molecular mass: the pterin of formylmethanofuran dehydrogenase was 400 Da larger than that of milk xanthine oxidase, a property also exhibited by the pterin cofactor of eubacterial molybdoenzymes. A homogeneous formylmethanofuran dehydrogenase preparation was used for these investigations. The enzyme, with a molecular mass of 220 kDa, contained 0.5-0.8 mol molybdenum, 0.6-0.9 mol pterin, 28 +/-2 mol non-heme iron and 28 +/-2 mol acid-labile sulfur/mol based on a protein determination with bicinchoninic acid. The specific activity was 175 mumol.min-1.mg-1 (kcat = 640 s-1) assayed with methylviologen (app. Km = 0.02 mM) as artificial electron acceptor. The apparent Km for formylmethanofuran was 0.02 mM. << Less

  Eur J Biochem 194:367-372(1990) [PubMed] [EuropePMC]