label: L-arginyl-[protein] + 2 S-adenosyl-L-methionine = N(omega),N(omega)'-dimethyl-L-arginyl-[protein] + 2 S-adenosyl-L-homocysteine + 2 H(+)
label_lc: l-arginyl-[protein] + 2 s-adenosyl-l-methionine = n(omega),n(omega)'-dimethyl-l-arginyl-[protein] + 2 s-adenosyl-l-homocysteine + 2 h(+)