label: 27-O-demethylrifamycin SV + S-adenosyl-L-methionine => rifamycin SV + S-adenosyl-L-homocysteine + H(+)
label_lc: 27-o-demethylrifamycin sv + s-adenosyl-l-methionine => rifamycin sv + s-adenosyl-l-homocysteine + h(+)