Si‐face stereospecificity at C5 of coenzyme F420 for F420‐dependent N5,N10‐methylenetetrahydromethanopterin dehydrogenase, F420‐dependent N5,N10‐methylenetetrahydromethanopterin reductase and F420H2:dimethylnaphthoquinone oxidoreductase

Abstract

Coenzyme F420‐dependent enzymes catalyze the reversible reduction of F420 by stereospecific hydride transfer to C5 of 5‐deazaflavin. Two F420‐dependent enzymes have been investigated with respect to the stereochemistry of hydride transfer, the F420‐dependent NADP reductase and the F420‐reducing hydrogenase. Both enzymes were found to be Si‐face specific. In this study we report that three additional F420‐dependent enzymes are also Si‐face specific: N5,N10‐methylenetetrahydromethanopterin dehydrogenase, N5,N10‐methylenetetrahydromethanopterin reductase and coenzyme F420H2: dimethylnaphthoquinone oxidoreductase (F420H2 dehydrogenase). Thus, all five characterized F420‐dependent enzymes are Si‐face specific, which is noteworthy since coenzyme F420 is functionally similar to pyridine nucleotides and both Si‐face specific and Re‐face specific pyridine‐nucleotide‐dependent enzymes exist. Copyright © 1993, Wiley Blackwell. All rights reserved