label: GTP + AH2 + S-adenosyl-L-methionine <=> (8S)-3',8-cyclo-7,8-dihydroguanosine 5'-triphosphate + 5'-deoxyadenosine + L-methionine + A + H(+)
label_lc: gtp + ah2 + s-adenosyl-l-methionine <=> (8s)-3',8-cyclo-7,8-dihydroguanosine 5'-triphosphate + 5'-deoxyadenosine + l-methionine + a + h(+)