In Vitro Synthesis of the Chlorophyll Isocyclic Ring 1: Transformation of Magnesium-Protoporphyrin IX and Magnesium-Protoporphyrin IX Monomethyl Ester into Magnesium-2,4-Divinyl Pheoporphyrin A5

摘要

Developing chloroplasts of Cucumis sativus L., cv Beit Alpha which were incubated with either Mg-protoporphyrin IX or Mg-protoporphyrin IX monomethyl ester in darkness produced a partially phototransformable protochlorophyllide species that was tentatively identified as Mg-2,4-divinyl pheoporphyrin a5. S-Adenosylmethionine stimulated Mg-2,4-divinyl pheoporphyrin a5 formation irrespective of the starting material used. In the case of Mg-protoporphyrin IX monomethyl ester, this stimulation was attributed to the need to remethylate substrate that had been hydrolyzed by an endogenous methylesterase which converts part of the added Mg-protoporphyrin IX monomethyl ester to Mg-protoporphyrin IX.