細(xì)胞如果在光照強(qiáng)度很高的條件下進(jìn)行光合作用,，將會(huì)產(chǎn)生一種極危險(xiǎn)的氧自由基,。但是在鞭毛藻(Dinoflagellates)細(xì)胞內(nèi)，卻有一種獨(dú)特的光捕獲復(fù)合體(light-harvesting complex),，能夠?qū)⒍嘤嗄芰坑行У剞D(zhuǎn)化為其他形式的能量,，從而避免細(xì)胞損傷。最近,，一項(xiàng)由美國和捷克的生物物理學(xué)家共同完成的研究中,，發(fā)現(xiàn)了在光捕獲復(fù)合體能量轉(zhuǎn)化過程中的一種重要的分子。這項(xiàng)研究發(fā)表在最近的PNAS雜志上。
鞭毛藻是一種重要的海洋浮游生物,，生活在10米以下的海水中,，鞭毛藻有一個(gè)重要的特征，能夠利用一種類胡蘿卜素——甲藻素(peridinin)作為光捕獲色素,。甲藻素能夠吸收從海水表面輻射到其生存環(huán)境中一定波長的光,。鞭毛藻的光捕獲復(fù)合體結(jié)構(gòu)很特別，以一個(gè)葉綠素分子為中心,，四周聚集著四個(gè)甲藻素分子,，從而形成甲藻素-葉綠素蛋白(peridinin-chlorophyll-protein,PCP)，甲藻素能夠捕獲光能,，并將光能高效地轉(zhuǎn)移到中心的葉綠素分子上,，研究人員推測(cè)，轉(zhuǎn)移到葉綠素分子上的能量還會(huì)轉(zhuǎn)移到其它光捕獲蛋白中,，最終進(jìn)入中心光系統(tǒng)實(shí)現(xiàn)能量的轉(zhuǎn)換并產(chǎn)生氧氣,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS November 23, 2009, doi: 10.1073/pnas.0908938106
Identification of a single peridinin sensing Chl-a excitation in reconstituted PCP by crystallography and spectroscopy
Tim Schultea,1, Dariusz M. Niedzwiedzkib,1,2, Robert R. Birgeb, Roger G. Hillerc, Tomá? Polívkad,e, Eckhard Hofmanna,3 and Harry A. Frankb,3
aBiophysics, Department of Biology and Biotechnology, Ruhr-University Bochum, D-44780 Bochum, Germany;
bDepartment of Chemistry, University of Connecticut, Storrs, CT 06269-3060;
cBiology Department, Faculty of Science, Macquarie University, NSW 2109, Australia;
dInstitute of Physical Biology, University of South Bohemia, 373-33 Nove Hrady, Czech Republic; and
eBiological Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
The peridinin-chlorophyll a-protein (PCP) of dinoflagellates is unique among the large variety of natural photosynthetic light-harvesting systems. In contrast to other chlorophyll protein complexes, the soluble PCP is located in the thylakoid lumen, and the carotenoid pigments outnumber the chlorophylls. The structure of the PCP complex consists of two symmetric domains, each with a central chlorophyll a (Chl-a) surrounded by four peridinin molecules. The protein provides distinctive surroundings for the pigment molecules, and in PCP, the specific environment around each peridinin results in overlapping spectral line shapes, suggestive of different functions within the protein. One particular Per, Per-614, is hypothesized to show the strongest electronic interaction with the central Chl-a. We have performed an in vitro reconstitution of pigments into recombinant PCP apo-protein (RFPCP) and into a mutated protein with an altered environment near Per-614. Steady-state and transient optical spectroscopic experiments comparing the RFPCP complex with the reconstituted mutant protein identify specific amino acid-induced spectral shifts. The spectroscopic assignments are reinforced by a determination of the structures of both RFPCP and the mutant by x-ray crystallography to a resolution better than 1.5 ?. RFPCP and mutated RFPCP are unique in representing crystal structures of in vitro reconstituted light-harvesting pigment-protein complexes.
