title: Purification and characterization of coenzyme F420-dependent 5,10-methylenetetrahydromethanopterin dehydrogenase from Methanobacterium thermoautotrophicum strain delta H.
abstract: 5,10-Methylenetetrahydromethanopterin dehydrogenase from Methanobacterium thermoautotrophicum strain delta H was purified to homogeneity with nearly complete recovery. The aerobically stable monofunctional enzyme catalyzed the reversible oxidation of 5,10-methylene-5,6,7,8-tetrahydromethanopterin to its 5,10-methenyl derivative. For the reaction a midpoint potential E'0 = - 362 mV was calculated at 60 degrees C. The methanogenic electron carrier coenzyme F420 was strictly required as the co-substrate. The dehydrogenase (Mr 216,000) was purified as an apparent hexamer of six identical 36 kDa subunits. Oxidation of 5,10-methylenetetrahydromethanopterin coupled to coenzyme F420 reduction catalyzed by the dehydrogenase with a turnover number of 2400 S-1 proceeded via a ternary complex mechanism. High concentrations of monovalent cations markedly stimulated the reaction.
authors.affiliation: Department of Microbiology, Faculty of Science; University of Nijmegen, The Netherlands.
authors.forename: B W
authors.initials: BW
authors.lastname: te Brömmelstroet
authors.forename: C M
authors.initials: CM
authors.lastname: Hensgens
authors.forename: J T
authors.initials: JT
authors.lastname: Keltjens
authors.forename: C
authors.initials: C
authors.lastname: van der Drift
authors.forename: G D
authors.initials: GD
authors.lastname: Vogels
mesh_terms: D019605:Euryarchaeota / Q000201:enzymology*; D007700:Kinetics; D008970:Molecular Weight; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D012256:Riboflavin / Q000031:analogs & derivatives / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: C015084:coenzyme F420; D000587:Oxidoreductases Acting on CH-NH Group Donors; C047126:methylenetetrahydromethanopterin dehydrogenase; D012256:Riboflavin