label: methenyltetrahydromethanopterin cyclohydrolase activity
label_lc: methenyltetrahydromethanopterin cyclohydrolase activity
description: "Catalysis of the reaction: 5,10-methenyl-5,6,7,8-tetrahydromethanopterin + H2O = N(5)-formyl-5,6,7,8-tetrahydromethanopterin + H+."