preferred_name: 2-[(3S)-3-carboxy-3-(methylamino)propyl]-L-histidyl-[translation elongation factor 2] + S-adenosyl-L-methionine <=> 2-[(3S)-3-carboxy-3-(dimethylamino)propyl]-L-histidyl-[translation elongation factor 2] + S-adenosyl-L-homocysteine + H(+)