CAROTENOID CHROMOPHORE LENGTH AND PROTECTION AGAINST PHOTOSENSITIZATION |
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| Authors: | Micheline M.,Mathews-Roth ,Thé rè se,Wilson ,Eiji,Fujimori Norman I.,Krinsky |
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| Affiliation: | Channing Laboratory, Thorndike Memorial Laboratory, Harvard Medical Unit and Dept. of Medical Microbiology, Boston City Hospital, Boston, Mass., 02118;Dept. of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Mass. 02115, U.S.A.;The Biological Laboratories, Harvard University, Cambridge, Mass. 02138, U.S.A.;Photochemistry Section, Energetics Branch, Space Physics Laboratory, Air Force Cambridge Research Laboratories, Bedford. Mass. 01730, U.S.A.;Dept. of Biochemistry and Pharmacology, Tufts University School of Medicine, Boston, Mass. 02111, U.S.A. |
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| Abstract: | Abstract— Carotenoid pigments were extracted and purified from wild-type and mutants 7 and 93a of Sarcina lutea , and tested for their ability to quench 1O2. The wild-type pigment (P-438, 9 conjugated double bonds) is as active in quenching 1O2 as is β-carotene. On the other hand, the pigment P-422 (8 conjugated double bonds) from mutant 7 is 2 or 3 times less efficient, whereas phytofluene and phytoene from S. lutea are 100 and 1000 times less efficient, respectively, than is β-carotene at quenching 1O2. It was also found that the broad EPR signal, induced by light in benzene solutions of chlorophyll a and hydroquinone, and related to chlorophyll oxidation, is efficiently quenched by P-438 and to a much smaller extent also by Sarcina phytoene. |
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