Chloroplast Biogenesis 65 : Enzymic Conversion of Protoporphyrin IX to Mg-Protoporphyrin IX in a Subplastidic Membrane Fraction of Cucumber Etiochloroplasts

摘要: The preparation from Percoll-purified cucumber (Cucumis sativus)etiochloroplasts of a subplastidic membrane fraction that is capable high rates Mg insertion into protoporphyrin IX described. plastid stroma was inactive when used either alone or in combination with the fraction. Successful required Mg-protoporphyrin chelatase first stabilized by its substrate. This achieved lysing plastids fortified hypotonic medium containing prior to ultracentrifugation and separation membranes. Protoporphyrin became bound. Other additives needed for enzyme activity fell two groups: (a) those stabilization during (b) involved primary mechanism IX. Ethylenediaminetetraacetate belonged group, magnesium second ATP both groups.