label: 3,3'-di-O-methyl-4alpha-mannobiose + S-adenosyl-L-methionine = 1,3,3'-tri-O-methyl-4alpha-mannobiose + S-adenosyl-L-homocysteine + H(+)
label_lc: 3,3'-di-o-methyl-4alpha-mannobiose + s-adenosyl-l-methionine = 1,3,3'-tri-o-methyl-4alpha-mannobiose + s-adenosyl-l-homocysteine + h(+)