Open AccessBacteriopheophytin g : Properties and some speculations on a possible primary role for bacteriochlorophylls b and g in the biosynthesis of chlorophylls
Author(s) -
T. J. Michalski,
Jerry E. Hunt,
Michael K. Bowman,
Ursula Smith,
K. Bardeen,
Howard Gest,
James R. Norris,
Joseph Katz
Publication year - 1987
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.84.9.2570
Subject(s) - bacteriochlorophyll , chemistry , pheophytin , photochemistry , stereochemistry , photosynthesis , biochemistry , photosystem ii
Bacteriopheophyting and small amounts of bacteriochlorophyllg have been obtained in high purity from the recently discovered photosynthetic bacteriumHeliobacterium chlorum . Preparative methods and precautions in handling these sensitive compounds are described. The compounds have been characterized by californium-252 plasma desorption mass spectrometry, HPLC, visible absorption, and electron spin resonance spectroscopy. Our results agree with the structure of bacteriochlorophyllg advanced by H. Brockmann and A. Lipinski [(1983)Arch. Microbiol . 136, 17-19], with the exception that we find the esterifying alcohol to be farnesol and not geranylgeraniol as originally suggested. Zero field splitting parameters of triplet state bacteriopheophyting and the ESR properties of the cation free radical of bacteriochlorophyllg are reported. The photoisomerization of the subject compounds has been studied. Bacteriopheophyting undergoes photo-isomerization in white light to pheophytina with a half-time of ≈42 min. We suggest that all of the chlorophylls are biosynthesized from a common intermediate containing an ethylidine group, [unk]CH—CH3 , such as is present in bacteriochlorophyllsb andg .