Publications

• Purification, properties and primary structure of H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase from Methanococcus thermolithotrophicus.

  Hartmann G.C., Klein A.R., Linder M., Thauer R.K.

  H2-Forming N5,N10 -methylenetetrahydromethanopterin dehydrogenase (Hmd) is a novel type of hydrogenase found in methanogenic Achaea that contains neither nickel nor iron-sulfur clusters. The enzyme has previously been characterized from Methanobacterium thermoautotrophicum and from Methanopyrus ka ... >> More

  H2-Forming N5,N10 -methylenetetrahydromethanopterin dehydrogenase (Hmd) is a novel type of hydrogenase found in methanogenic Achaea that contains neither nickel nor iron-sulfur clusters. The enzyme has previously been characterized from Methanobacterium thermoautotrophicum and from Methanopyrus kandleri. We report here on the purification and properties of the enzyme from Methanococcus thermolithotrophicus. The hmd gene was cloned and sequenced. The results indicate that the enzyme from Mc. thermolithotrophicus is functionally and structurally closely related to the H2-forming methylene tetrahydromethanopterin dehydrogenase from Mb. thermoautotrophicum and Mp. kandleri. From amino acid sequence comparisons of the three enzymes, a phylogenetic tree was deduced that shows branching orders similar to those derived from sequence comparisons of the 16S rRNA of the orders Methanococcales, Methanobacteriales, and Methanopyrales. << Less

  Arch. Microbiol. 165:187-193(1996) [PubMed] [EuropePMC]

• H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase: mechanism of H2 formation analyzed using hydrogen isotopes.

  Klein A.R., Fernandez V.M., Thauer R.K.

  H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase catalyzes the reversible dehydrogenation of N5,N10-methylenetetrahydromethanopterin (CH2 = H4MPT) to N5,N10-methenyltetrahydromethanopterin (CH = H4MPT+) and H2. In D2O both HD and D2 are formed from CH2 = H4MPT and in H2O both HD an ... >> More

  H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase catalyzes the reversible dehydrogenation of N5,N10-methylenetetrahydromethanopterin (CH2 = H4MPT) to N5,N10-methenyltetrahydromethanopterin (CH = H4MPT+) and H2. In D2O both HD and D2 are formed from CH2 = H4MPT and in H2O both HD and H2 from CD2 = H4MPT. Evidence is presented that HD is not an intermediate in the formation of D2 and H2, respectively. << Less

  FEBS Lett 368:203-206(1995) [PubMed] [EuropePMC]

• H2-forming N5, N10-methylenetetrahydromethanopterin dehydrogenase from Methanobacterium thermoautotrophicum catalyzes a stereoselective hydride transfer as determined by two-dimensional NMR spectroscopy.

  Schleucher J., Griesinger C., Schworer B., Thauer R.K.

  5,6,7,8-Tetrahydromethanopterin is a coenzyme playing a key role in the energy metabolism of methanogenic archaea. In Methanobacterium thermoautotrophicum, the reduction of N5, N10-methenyl-5,6,7,8-tetrahydromethanopterin at C(14a) with H2 to N5, N10-methylene-5,6,7,8-tetrahydromethanopterin can b ... >> More

  5,6,7,8-Tetrahydromethanopterin is a coenzyme playing a key role in the energy metabolism of methanogenic archaea. In Methanobacterium thermoautotrophicum, the reduction of N5, N10-methenyl-5,6,7,8-tetrahydromethanopterin at C(14a) with H2 to N5, N10-methylene-5,6,7,8-tetrahydromethanopterin can be catalyzed by H2-forming methylenetetrahydromethanopterin dehydrogenase, a new hydrogenase present in most methanogenic archaea, which is unique because it does not contain nickel or iron/sulfur clusters. In this work, the stereochemistry of this enzymatic hydride-transfer reaction is elucidated by means of a series of heteronuclear two-dimensional NMR experiments. It is found that the hydride from H2 is transferred by the enzyme into the rel-(pro-R) position of the C(14a) methylene group of the reaction product N5, N10-methylene-5,6,7,8-tetrahydromethanopterin. NMR experiments are described that show that the hydrogen nucleus of the hydride transferred to the oxidized coenzyme partially originates from water. The stereochemical course of this reaction is the same as that for direct hydride transfer. It is demonstrated that the diastereotopic atoms at C(14a) of the reaction product epimerize in an uncatalyzed reaction under the conditions of operation of the enzyme (k = 0.01 s-1 at 58 degree C and pH 6.5).(ABSTRACT TRUNCATED AT 250 WORDS) << Less

  Biochemistry 33:3986-3993(1994) [PubMed] [EuropePMC]

• Participative management.

  Wheeler A.

  Nurs Times 74:469-470(1978) [PubMed] [EuropePMC]