Chloroplast biogenesis. Detection of monovinyl magnesium-protoporphyrin monoester and other monovinyl magnesium-porphyrins in higher plants.

Abstract

It is shown that the magnesium-protoporphyrin-6-ester pool of plants is made up of monovinyl and divinyl components which were separated by chromatography on thin layers of polyethylene. At 77K, in ether, monovinyl-Mg-protoporphyrin-6-ester exhibited fluorescence emission and excitation maxima at 589 and 417 nm, respectively. The divinyl-Mg-protoporphyrin-6-ester component exhibited red-shifted emission and excitation maxima at 591 and 424 nm respectively. Demetallation of the monovinyl and divinyl Mg-protoporphyrin ester components converted them into monovinyl and divinyl-protoporphyrin IX free bases. Catalytic Mg-mesoporphyrin ester and the demetallated free bases into mesoporphyrin ester, Monovinyl-Mg-porphyrin chemical species were also detected in the Mg-protoporphyrin IX and the Mg-protoporphyrin IX diester pools of plants. It is proposed that the Mg-protoporphyrin IX, Mg-protoporphyrin IX-6-ester, and Mg-protoporphyrin IX-diester pools of plants are heterogenous and are made up of monovinyl and divinyl chemical species.