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Full-Text Articles in Molecular Biology
Anaerobic Protoporphyrin Biosynthesis Does Not Require Incorporation Of Methyl Groups From Methionine, David Bollivar, Thomas Elliott, Samuel I. Beale
Anaerobic Protoporphyrin Biosynthesis Does Not Require Incorporation Of Methyl Groups From Methionine, David Bollivar, Thomas Elliott, Samuel I. Beale
David Bollivar
It was recently reported (H. Akutsu, J.-S. Park, and S. Sano, J. Am. Chem. Soc. 115:12185–12186, 1993) that in the strict anaerobe methyl groups from exogenous L-methionine are incorporated specifically into the 1 and 3 positions (Fischer numbering system) on the heme groups of cytochrome c3. It was suggested that under anaerobic conditions, protoporphyrin IX biosynthesis proceeds via a novel pathway that does not involve coproporphyrinogen III as a precursor but instead may use precorrin-2 (1,3-dimethyluroporphyrinogen III), a siroheme and vitamin B12 precursor which is known to be derived from uroporphyrinogen III via methyl transfer from S-adenosyl-L-methionine. We have critically …
Formation Of The Isocyclic Ring Of Chlorophyll By Isolated Clamydomonas Reinhardtii Chloroplasts, David Bollivar, Samuel I. Beale
Formation Of The Isocyclic Ring Of Chlorophyll By Isolated Clamydomonas Reinhardtii Chloroplasts, David Bollivar, Samuel I. Beale
David Bollivar
Chlamydomonas reinhardtii chloroplasts catalyzed two sequential steps of Chl biosynthesis, S-adenosyl-L-methionine:Mg-protoporphyrin IX methyltransferase and Mg-protoporphyrin IX monomethyl ester oxidative cyclase. A double mutant strain of C. reinhardtii was constructed which has a cell wall deficiency and is unable to form chlorophyll in the dark. Dark-grown cells were disrupted with a BioNeb nebulizer under conditions which lysed the plasma membrane but not the chloroplast envelope. Chloroplasts were purified by Percoll density gradient centrifugation. The purified chloroplasts were used to define components required for the biosynthesis of Mg-2,4-divinylpheoporphyrin a 5 (divinyl protochlorophyllide) from Mg-protoporphyrin IX. Product formation requires the addition of Mg-protoporphyrin …