label: L-methionyl-[protein] + S-adenosyl-L-methionine = S-methyl-L-methionyl-[protein] + S-adenosyl-L-homocysteine
label_lc: l-methionyl-[protein] + s-adenosyl-l-methionine = s-methyl-l-methionyl-[protein] + s-adenosyl-l-homocysteine