label: magnesium protoporphyrin IX methyltransferase activity
label_lc: magnesium protoporphyrin ix methyltransferase activity
description: "Catalysis of the reaction: Mg-protoporphyrin IX + S-adenosyl-L-methionine = Mg-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-homocysteine."