PHOTOSYNTHETICA

Photosynthetica 2007, 45(2):266-271 | DOI: 10.1007/s11099-007-0043-z

Energy transfer of aromatic amino acids in photosystem 2 core antenna complexes CP43 and CP47

Y. G. Qu^1,2, X. C. Qin¹, W. F. Wang², L. B. Li^1,*, T. Y. Kuang^1,*

¹ Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing, China

² College of Life Sciences, Linyi Normal University, Linyi, China

Energy transfer of aromatic amino acids in photosystem 2 (PS2) core antenna complexes CP43 and CP47 was studied using absorption spectroscopy, fluorescence spectroscopy, and the 0.35 nm crystal structure of PS2 core complex. The energy of tyrosines (Tyrs) was not effectively transferred to tryptophans (Trps) in CP43 and CP47. The fluorescence emission spectrum of CP43 and CP47 by excitation at 280 nm should be a superposition of the Tyr and Trp fluorescence emission spectra. The aromatic amino acids in CP43 and CP47 could transfer their energy to chlorophyll (Chl) a molecules by the Dexter mechanism and the Föster mechanism, and the energy transfer efficiency in CP47 was much higher than that in CP43. In CP47 the Föster mechanism must be the dominant energy transfer mechanism between aromatic amino acids and Chl a molecules, whereas in CP43 the Dexter mechanism must be the dominant one. Hence solar ultraviolet radiation brings not only damages but also benefits to plants.

Additional key words: absorption; β-carotene; chlorophyll; fluorescence; model; proteins; tryptophan; tyrosine

Received: June 30, 2006; Accepted: November 6, 2006; Published: June 1, 2007  Show citation