4-amino-4-dedimethylamino-anhydrotetracycline + S-adenosyl-L-methionine => 4-methylamino-4-dedimethylamino-anhydrotetracycline + S-adenosyl-L-homocysteine + H(+)
4-amino-4-dedimethylamino-anhydrotetracycline + s-adenosyl-l-methionine => 4-methylamino-4-dedimethylamino-anhydrotetracycline + s-adenosyl-l-homocysteine + h(+)