label: rebeccamycin + S-adenosyl-L-homocysteine + H(+) => 4'-demethylrebeccamycin + S-adenosyl-L-methionine
label_lc: rebeccamycin + s-adenosyl-l-homocysteine + h(+) => 4'-demethylrebeccamycin + s-adenosyl-l-methionine