Purification and properties of 5,10-methylenetetrahydromethanopterin reductase, a coenzyme F420-dependent enzyme, from Methanobacterium thermoautotrophicum strain delta H

• Published in: The Journal of biological chemistry 1990-02, Vol.265 (4), p.1852-1857
• Main Authors: TE BROMMELSTROET, B. W, HENSGENS, C. M. H, KELTJENS, J. T, VAN DER DRIFT, C, VOGELS, G. D
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chromatography, Ion Exchange; Coenzymes, vitamins; Euryarchaeota - enzymology; Fundamental and applied biological sciences. Psychology; Indicators and Reagents; Kinetics; Molecular Weight; Other biological molecules; Oxidoreductases Acting on CH-NH Group Donors - isolation & purification; Oxidoreductases Acting on CH-NH Group Donors - metabolism; Riboflavin - analogs & derivatives; Riboflavin - metabolism; Substrate Specificity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(19)39907-7

5,10-Methylenetetrahydromethanopterin reductase was purified 22-fold to apparent homogeneity from the methanogenic bacterium Methanobacterium thermoautotrophicum. The enzyme catalyzes the reduction of 5,10-methylene- to 5-methyltetrahydromethanopterin. The electron carrier coenzyme F420 is specifically used as the cosubstrate. The reductase reaction may proceed in both directions, methylene reduction is, however, thermodynamically favored. In addition, the velocity of the reaction in this direction exceeds the reverse reaction by a factor of 26. The reductase is composed of a single subunit with an estimated Mr = 35,000. The active enzyme does not contain a flavin prosthetic group or iron-sulfur clusters, in contrast to 5,10-methylenetetrahydrofolate reductases purified from eukaryotic and eubacterial sources, which catalyze an analogous reaction as the methanogenic reductase.