Radmer R J, Bogorad L
Plant Physiol. 1967 Mar;42(3):463-5. doi: 10.1104/pp.42.3.463.
The enzyme (-) S-adenosyl-L-methionine-magnesium protoporphyrin methyltransferase, which catalyzes the transfer of the methyl group from (-) S-adenosyl-L-methionine to magnesium protoporphyrin to form magnesium protoporphyrin monomethyl ester, has been detected in chloroplasts isolated from Zea mays. Zinc protoporphyrin and free protoporphyrin also act as substrates in the system, although neither one is as active as magnesium protoporphyrin. THE FOLLOWING SCHEME OF CHLOROPHYLL SYNTHESIS IN HIGHER PLANTS IS PROPOSED: delta-aminolevulinic acid --> --> --> protoporphyrin --> magnesium protoporphyrin --> magnesium protoporphyrin monomethyl ester --> --> --> chlorophyll a.
（-）S-腺苷-L-甲硫氨酸-镁原卟啉甲基转移酶可催化（-）S-腺苷-L-甲硫氨酸上的甲基转移至镁原卟啉，形成镁原卟啉单甲酯。已在从玉米中分离出的叶绿体中检测到该酶。锌原卟啉和游离原卟啉在该体系中也可作为底物，尽管它们的活性均不如镁原卟啉。现提出高等植物叶绿素合成的如下途径：δ-氨基乙酰丙酸→→→原卟啉→镁原卟啉→镁原卟啉单甲酯→→→叶绿素a。
