Abstract
The tyrosine-(M)210 of the reaction center of Rhodobacter sphaeroides 2.4.1 has been changed to a tryptophan using site-directed mutagenesis. The reaction center of this mutant has been characterized by low-temperature absorption and fluorescence spectroscopy, time-resolved sub-picosecond spectroscopy, and magnetic resonance spectroscopy. The charge separation process showed bi-exponential kinetics at room temperature, with a main time constant of 36 ps and an additional fast time constant of 5.1 ps. Temperature dependent fluorescence measurements predict that the lifetime of P* becomes 4–5 times slower at cryogenic temperatures. From EPR and absorbance-detected magnetic resonance (ADMR, LD-ADMR) we conclude that the dimeric structure of P is not significantly changed upon mutation. In contrast, the interaction of the accessory bacteriochlorophyll BA with its environment appears to be altered, possibly because of a change in its position.
Item Type: | Journal article |
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Keywords: | absorption spectrum, ADMR, charge separation, fluorescence spectrum, reaction center, mutant |
Faculties: | Physics |
Subjects: | 500 Science > 530 Physics |
URN: | urn:nbn:de:bvb:19-epub-3780-7 |
ISSN: | 0166-8595 |
Item ID: | 3780 |
Date Deposited: | 09. May 2008, 10:37 |
Last Modified: | 08. May 2024, 08:14 |