Demethylrebeccamycin-D-glucose O-methyltransferase (, RebM) is an enzyme with systematic name S-adenosyl-L-methionine:demethylrebeccamycin-D-glucose O-methyltransferase. This enzyme catalyses the following chemical reaction
This is the final step in the biosynthesis of rebeccamycin, an indolocarbazole alkaloid isolated from Nocardia bacteria. It uses S-adenosyl methionine as a cofactor.