label: L-lysyl(9)-[histone H3] + 2 S-adenosyl-L-methionine = N(6),N(6)-dimethyl-L-lysyl(9)-[histone H3] + 2 S-adenosyl-L-homocysteine + 2 H(+)
label_lc: l-lysyl(9)-[histone h3] + 2 s-adenosyl-l-methionine = n(6),n(6)-dimethyl-l-lysyl(9)-[histone h3] + 2 s-adenosyl-l-homocysteine + 2 h(+)