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SYBM: Physik biologischer Materie

SYBM 401: Physics of biological matter: Poster

SYBM 401.36: Poster

Dienstag, 12. März 2002, 18:00–19:30, H37

Energy relaxation in LH1 complexes of mutants from Rhodospirillum rubrum with and without carotenoids of different conjugation lengths — •Peter Gärtner¹, Marcus Branschädel², Robin Ghosh², and Helmut Port¹ — ¹3. Physikalisches Institut, Universität Stuttgart — ²Biologisches Institut, Abt. Bioenergetik, Universität Stuttgart

The light-harvesting complex 1 from Rhodospirillum rubrum was isolated from mutants ST4 and S1 containing the carotenoid 3,4,3’,4’-tetrahydrospirilloxanthin (thSpx) and spirilloxanthin (Spx), respectively, as well as from G9, lacking carotenoid. ThSpx and Spx extracted from the complexes and dissolved in n-hexane were used as reference samples. In these systems energy relaxation was studied by femtosecond transient absorption measurements in contrast to the Spx containing complexes (wild type) the thSpx absorption bands do not overlap with the Q_x band of BChl, thus allowing selective excitation. The primary aim is to distinguish competing internal conversion processes from inter-pigment energy transfer. The results allow to distinguish three fundamental processes. The interpretation of the data will be discussed.