Ultrafast Two-Photon Spectroscopy of Carotenoids involved in the Regulation of Photosynthesis

参与光合作用调节的类胡萝卜素的超快双光子光谱

• 批准号: 31763058
• 负责人: Professor Dr. Peter Jomo Walla
• 金额: --
• 依托单位: Institut für Physikalische und Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/31763058?language=en
• 关键词: Ultrafast; Two; Photon; Spectroscopy; Carotenoids

A quick balancing between utilization and dissipation of absorbed light energy is essential for the survival of natural and gene modified plants.[1-3] However, despite intensive investigations (see recent publications in Nature and Science)[1, 4-6] the biophysical mechanisms of these regulation processes are still poorly understood. The molecular gear shift model proposes that a reversible and step-wise enzymatic modification of the chemical structure of xanthophyll carotenoids enables a switching between carotenoid-to-chlorophyll lightharvesting and chlorophyll-to-carotenoid quenching.[7] Unfortunately, the involved firstexcited singlet state of the carotenoids, Car S1, is optically forbidden[8] which renders impossible a direct investigation of its role by conventional absorption or fluorescence spectroscopy. In the past we have shown that two-photon excitation (TPE) allows a selective population of the forbidden state because the optical selection rules are different for this nonlinear process.[9-15] Preliminary two-photon sensitized fluorescence experiments[9] indicated that the proposed change in carotenoid-chlorophyll energy flow indeed takes place in plants. We now plan to investigate isolated pigment-protein complexes as well as thylakoid and chloroplast preparations containing well defined amounts of high- or low-light xanthophylls. The aim of these two-photon experiments is to provide a clear prove or disprove for a major contribution of the proposed mechanism and to elucidate which of the pigment-protein complexes are involved in such a regulation.

快速平衡吸收光能的利用和耗散对于天然植物和转基因植物的生存至关重要。[1-3]然而，尽管进行了大量的研究(参见最近发表在《自然》和《科学》上的文章)[1，4-6]这些调节过程的生物物理机制仍然知之甚少。分子轮换模型认为，可逆酶促类胡萝卜素化学结构的改变使得类胡萝卜素从光收获到类胡萝卜素和从类胡萝卜素到类胡萝卜素猝灭之间发生转换。[7]不幸的是，类胡萝卜素的第一激发单线态CAR S1在光学上是被禁止的[8]，这使得用传统的吸收光谱或荧光光谱不可能直接研究它的作用。在过去，我们已经证明，双光子激发(TPE)允许选择性地布居禁态，因为对于这个非线性过程，光学选择规则是不同的。[9-15]初步的双光子敏化荧光实验[9]表明，所提出的类胡萝卜素-叶绿素能流的变化确实发生在植物中。我们现在计划研究分离的色素-蛋白质复合体，以及含有明确数量的高光或弱光叶黄素的类囊体体和叶绿体制剂。这些双光子实验的目的是为所提出的机制的主要贡献提供明确的证明或反驳，并阐明哪些色素-蛋白质复合体参与了这种调节。