INVESTIGATIONS OF BIOGENESIS OF CHLOROPHYLL A .4. ISOLATION AND PARTIAL CHARACTERIZATION OF SOME BIOSYNTHETIC INTERMEDIATES BETWEEN MG-PROTOPORPHINE 9 MONOMETHYL ESTER AND MG-VINYLPHEOPORPHINE A5 OBTAINED FROM CHLORELLA MUTANTS

Through the use of mass, visible, and IR spectrometry on chromatographically-separated bands of esterified porphyrins and their derivatives obtained from Chlorella mutants AJ and BE, structures have been determined which appear to be the intermediates between Mg-protoporphine IX-65 methyl ester and protochlorophyllide a in the chlorophyll a pathway. A metabolic sequence is proposed which involves β-oxidation of the 62-propionate side chain to the 63-keto- derivative, which is then condensed with the γ-methine carbon to form the isocyclic ring of chlorophyll a. Reduction of the 42-vinyl- to the pheoporphine stage appears to be less specific, and possibly random. The β-oxidation sequence occurs for both the mono- and divinylprotoporphine IX compounds. The proposed Δ63-protoporphine IX compounds were not isolated, but their presence was inferred in the protoporphine IX band. The corresponding Mg chelates of the above porphyrins were isolated. © 1969.