PHOTOREACTIVATION OF Halobacterium halobium: ACTION SPECTRUM AND ROLE OF PIGMENTATION |
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Authors: | Tatsuo Iwasa Satoru Tokutomi Fumio Tokunaga |
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Institution: | Department of Physics, Faculty of Science, Tohoku University, Aobayama, Sendai 980, Japan;National Institute for Basic Biology, Okazaki National Research Institutes, Okazaki, Aichi 444, Japan |
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Abstract: | Abstract— An action spectrum for photoreactivation was measured with Halobacterium halobium R1m1 to prove a role of carotenoid pigments in photoreactivation of the bacteria. The action spectrum obtained showed a main peak at 435 nm and a minor peak at about 325 nm. The action spectrum was similar to that of Streptomyces pigment (Eker et al. , 1981) suggesting that the chromophore of the photoreactivating enzyme in Halobacterium halobium is 8-OH-5-deazaflavin. The minor peak may be due to photochemical cleavage of a pyrimidine6–4 hetero adduct. The result indicates that carotenoid pigments do not play a positive role in enhancing photoreactivation. This was confirmed also by comparing the efficiency of photoreactivation at 465 nm among three strains of Halobacterium halobium having different carotenoid pigments; R1m1. R1 and W5002–1. |
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