N-methyl-dopamine + S-adenosyl-L-methionine <=> N,N-dimethyldopamine + S-adenosyl-L-homocysteine + H(+)
n-methyl-dopamine + s-adenosyl-l-methionine <=> n,n-dimethyldopamine + s-adenosyl-l-homocysteine + h(+)
N-methyl-dopamine + S-adenosyl-L-methionine <=> N,N-dimethyldopamine + S-adenosyl-L-homocysteine + H(+)
n-methyl-dopamine + s-adenosyl-l-methionine <=> n,n-dimethyldopamine + s-adenosyl-l-homocysteine + h(+)