PURIFICATION AND CHARACTERIZATION OF COENZYME-F420-DEPENDENT 5,10-METHYLENETETRAHYDROMETHANOPTERIN DEHYDROGENASE FROM METHANOBACTERIUM-THERMOAUTOTROPHICUM STRAIN DELTA-H

被引:29
作者
BROMMELSTROET, BWT [1 ]
HENSGENS, CMH [1 ]
KELTJENS, JT [1 ]
VANDERDRIFT, C [1 ]
VOGELS, GD [1 ]
机构
[1] UNIV NIJMEGEN,FAC SCI,DEPT MICROBIOL,6225 ED NIJMEGEN,NETHERLANDS
关键词
METHYLENETETRAHYDROMETHANOPTERIN DEHYDROGENASE; 5,6,7,8-TETRAHYDROMETHANOPTERIN; COENZYME-F420; DEAZAFLAVIN; METHANOGENESIS; (M-THERMOAUTOTROPHICUM);
D O I
10.1016/0304-4165(91)90185-J
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
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 E0' = -362 mV was calculated at 60-degrees-C. The methanogenic electron carrier coenzyme F420 was strictly required as the co-substrate. The dehydrogenase (M(r) 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.
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页码:77 / 84
页数:8
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