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DARK REACTIONS FOLLOWING PHOTOISOMERIZATION OF PROLYCOPENE *
Author(s) -
RÖMER SUSANNE,
HUMBECK KLAUS,
SENGER HORST
Publication year - 1991
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1991.tb03666.x
Subject(s) - isomerization , darkness , photoisomerization , chemistry , xanthophyll , mutant , carotenoid , scenedesmus obliquus , biosynthesis , photochemistry , lycopene , stereochemistry , biochemistry , botany , biology , algae , enzyme , catalysis , gene
— Cells of mutant C‐6D of the unicellular green alga Scenedesmus obliquus form only acyclic carotenoid precursors up to prolycopene (7Z, 9Z, 7′Z, 9′Z cis ‐isomer of lycopene) when grown heterotrophically in the dark. Upon illumination, however, the cyclic carotenes α‐ and β‐carotene and the xanthophylls are synthesized. Inhibition of the cyclization reaction by nicotine revealed a light‐induced isomerization of prolycopene accumulated in darkness to all‐ trans lycopene. The following reactions, e. g. cyclization and oxidations, take place in light as well as in darkness. The results presented here demonstrate that the isomerization of prolycopene into the all‐ trans form is the only light‐dependent step in carotenogenesis of mutant C‐6D. Finally, a model showing the light‐regulation of carotenoid biosynthesis in mutant C‐6D of S. obliquus is presented.