唧唧堂编辑二朵2014-05-19 7:00 PM

光谱学与量子化学模拟揭示了激子相互作用对α-甲壳蓝蛋白(螯龙虾背甲中的蓝色胡萝卜素蛋白)红移的主要贡献 Spectroscopy and quantum chemical modeling reveal a predominant contribution of excitonic interactions to the bathochromic shift in alpha-crustacyanin, the blue carotenoprotein in the carapace of the lobster Homarus gammarus.

论文摘要


要解决α- 虾青蛋白着色机制的分子基础,我们用(13)C-标记的虾青素类作为固态(13)C-NMR和[6,6',7,7']–(13)C(4)α- 虾青蛋白以及[8,8',9,9',10,10',11,11', 20,20']-(13)C(10)α- 虾青蛋白的共振拉曼光谱的发色团。我们基于可用于β-虾青蛋白的结构信息的几种模式上的时间依赖密度泛函理论运算来补充实验数据。该数据排除了结合到蛋白质上的虾青素的基态电子密度的主要变化和强极化效应。虾青素和蛋白质之间的发色团和氢键相互作用中的构象变化只占α-虾青蛋白 总红移的约三分之一。我们发现2个虾青素生色团接近产生的激子耦合很大,这表明蛋白质中的聚集效应代表了颜色变化的主要来源。


Abstract 


To resolve the molecular basis of the coloration mechanism of alpha-crustacyanin, we used (13)C-labeled astaxanthins as chromophores for solid-state (13)C NMR and resonance Raman spectroscopy of [6,6',7,7']-(13)C(4) alpha-crustacyanin and [8,8',9,9',10,10',11,11',20,20']-(13)C(10) alpha-crustacyanin. We complement the experimental data with time-dependent density functional theory calculations on several models based on the structural information available for beta-crustacyanin. The data rule out major changes and strong polarization effects in the ground-state electron density of astaxanthin upon binding to the protein. Conformational changes in the chromophore and hydrogen-bond interactions between the astaxanthin and the protein can account only for about one-third of the total bathochromic shift in alpha-crustacyanin. The exciton coupling due to the proximity of two astaxanthin chromophores is found to be large, suggesting that aggregation effects in the protein represent the primary source of the color change.

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