N(1)-(5-phospho-beta-D-ribosyl)glycinamide + (6R)-5,10-methenyltetrahydrofolate + H2O <=> N(2)-formyl-N(1)-(5-phospho-beta-D-ribosyl)glycinamide + (6S)-5,6,7,8-tetrahydrofolate + 2 H(+)
n(1)-(5-phospho-beta-d-ribosyl)glycinamide + (6r)-5,10-methenyltetrahydrofolate + h2o <=> n(2)-formyl-n(1)-(5-phospho-beta-d-ribosyl)glycinamide + (6s)-5,6,7,8-tetrahydrofolate + 2 h(+)