The enzyme, characterized from the bacterium Methylobacterium extorquens, is involved in biosynthesis of dephospho-tetrahydromethanopterin. The specific activity with NADH is 15% of that with NADPH at the same concentration [1]. It does not reduce 7,8-dihydrofolate (cf. EC 1.5.1.3, dihydrofolate reductase).