RE-FACE SPECIFICITY AT C14A OF METHYLENETETRAHYDROMETHANOPTERIN AND SI-FACE SPECIFICITY AT C5 OF COENZYME F-420 FOR COENZYME F-420-DEPENDENT METHYLENETETRAHYDROMETHANOPTERIN DEHYDROGENASE FROM METHANOGENIC ARCHAEA

Coenzyme F-420-dependent methylenetetrahydromethanopterin dehydrogenase from methanogenic Archaea catalyzes the reversible transfer of a hydride ion from C14a of N-5,N-10-methylenetetrahydromethanopterin to C5 of coenzyme F-420. In this study, we report that this hydride transfer proceeds stereospecifically from the Re face at C14a to the Si face at C5. The results were obtained by using chirally H-3-labelled N-5,N-10-methylenetetrahydromethanopterin generated via Re-face-specific H-2-forming N-5,N-10-methylenetetrahydromethanopterin dehydrogenase and by analyzing reduced coenzyme F-420 via Si-face-specific F-420-reducing hydrogenase.