5,6,7,8-tetrahydromethanopterin + A <=> 7,8-dihydromethanopterin + AH2
5,6,7,8-tetrahydromethanopterin + a <=> 7,8-dihydromethanopterin + ah2
5,6,7,8-tetrahydromethanopterin + A <=> 7,8-dihydromethanopterin + AH2
5,6,7,8-tetrahydromethanopterin + a <=> 7,8-dihydromethanopterin + ah2