This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.104.049916v1 88/3/1959    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gibasiewicz, K. Articles by van Grondelle, R. Search for Related Content PubMed PubMed Citation Articles by Gibasiewicz, K. Articles by van Grondelle, R.

Excitation Energy Transfer Pathways in Lhca4

K. Gibasiewicz ^* , R. Croce , T. Morosinotto  ^¶, J. A. Ihalainen ^*, I. H. M. van Stokkum ^*, J. P. Dekker ^*, R. Bassi  ^¶ and R. van Grondelle ^*

^* Faculty of Sciences, Division of Physics and Astronomy, Department of Biophysics, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands; Department of Physics, Adam Mickiewicz University, 61-614 Pozna, Poland; Istituto di Biofisica, CNR, Trento, c/o ITC Povo, Trento 38100, Italy; Dipartimento Scientifico e Tecnologico, Università di Verona, 15-37134 Verona, Italy; and ^¶ Université Aix-Marseille II, LGBP, Faculté des Sciences de Luminy, Département de Biologie, Case 901, 13288 Marseille, France

Correspondence: Address reprint requests to Rienk van Grondelle, Tel.: 31-20-444-7930; E-mail: rienk{at}nat.vu.nl.

EET in reconstituted Lhca4, a peripheral light-harvesting complex from Photosystem I of Arabidopsis thaliana, containing 10 chlorophylls and 2 carotenoids, was studied at room temperature by femtosecond transient absorption spectroscopy. Two spectral forms of Lut were observed in the sites L1 and L2, characterized by significantly different interactions with nearby chlorophyll a molecules. A favorable interpretation of these differences is that the efficiency of EET to Chls is about two times lower from the "blue" Lut in the site L1 than from the "red" Lut in the site L2 due to fast IC in the former case. A major part of the energy absorbed by the "red" Lut, 60%–70%, is transferred to Chls on a sub-100-fs timescale from the state S₂ but, in addition, minor EET from the hot S₁ state within 400–500 fs is also observed. EET from the S₁ state to chlorophylls occurs also within 2–3 ps and is ascribed to Vio and/or "blue" Lut. EET from Chl b to Chl a is biphasic and characterized by time constants of 300 fs and 3.0 ps. These rates are ascribed to EET from Chl b spectral forms absorbing at 644 nm and 650 nm, respectively. About 25% of the excited Chls a decays very fast—within 15 ps. This decay is proposed to be related to the presence of the interacting Chls A5 and B5 located next to the carotenoid in the site L2 and may imply some photoprotective role for Lhca4 in the photosystem I super-complex.

This article has been cited by other articles:

				P. Zuo, B.-X. Li, X.-H. Zhao, Y.-S. Wu, X.-C. Ai, J.-P. Zhang, L.-B. Li, and T.-Y. Kuang Ultrafast Carotenoid-to-Chlorophyll Singlet Energy Transfer in the Cytochrome b6f Complex from Bryopsis corticulans Biophys. J., June 1, 2006; 90(11): 4145 - 4154. [Abstract] [Full Text] [PDF]