光激发铁卟啉蛋白能量与电子转移机制研究

Magnesium porphyrin (chlorophyll) in vivo plays an important role in absorption/conversion light energy. However, the iron-porphyrin (heme) in proteins, which usually expresses its function in dark environments, has been largely neglected in photo induced redox reactions. In recent years, with spectroscopy experiments, we discovered and proved that oxidation-reduction reactions in the iron-porphyrin proteins can be induced when the proteins absorb special wavelength lights in ultraviolet/visible region within a reasonable time. The iron-porphyrins can absorb the light and cause the variation of its ionic potential and electron affinity, lead to the energy transfer and electronic transfer process and generate some excited state intermediates in the photo-exited process. Unfortunately, the molecular mechanisms of the photo reaction are still not completely and clearly elaborated based on the current data. In this research project, myoglobin and cytochrome c are selected as research models for investigating of the mechanism of photo induced redox reaction, including the illustration of dynamic variations of the Sn excited states decaying process with the application of laser flash photolysis, the determination of photo reaction intermediates of the photo reactions with the utilizations of gas online mass spectroscopy and electronic paramagnetic resonance. With various theory approaches, such as density functional theory and time dependent density function theory, Marcus electronic transition theory, QM/MM and molecular dynamics, we attempt to comprehend the energy and electron transfer process in the proteins and the subsequent photochemical reactions. With the presence of various amino acids, gas and water, different kinetics and dynamic mechanism of photo induced reactions shall be illustrated by our experimental data and theory researches. The research results of this project can be applied in meat preservation and photodynamic therapy of iron-porphyrin protein related diseases.

生物体内镁卟啉（叶绿素）在吸收/转化光能中发挥重要作用，但铁卟啉（血红素）蛋白正常功能表达一般在暗条件下进行，这类蛋白光激发反应一直未引起重视。我们近年来发现并证实合理时间内用紫外可见区特定波长光照铁卟啉蛋白可引发其氧化还原反应，光激发卟啉到其电子激发态，改变卟啉的电离势和电子亲和能，反应过程中伴随着铁卟啉能量/电子转移和激发态中间体的产生等，但目前尚未清晰理解完整的光反应分子机制。因此本课题选取肌红蛋白和细胞色素c等铁卟啉蛋白，实验上运用激光闪光光解监测铁卟啉分子激发态Sn在衰减过程中的动态变化，运用气体在线质谱和电子顺磁共振技术等确定光反应中间体等；理论上运用DFT/TD-DFT、Marcus电子转移理论和QM/MM等理解光激发铁卟啉蛋白分子内从电子供体到电子受体的能量/电子转移过程和后续的光化学反应过程。本研究在肉类保鲜及光动力治疗与此类蛋白相关的疾病等方面有重要应用价值。

生物体内镁卟啉（叶绿素）在吸收/转化光能中发挥重要作用，但铁卟啉（血红素）蛋白正常功能表达一般在暗条件下进行，这类蛋白光激发反应一直未引起重视。我们近年来发现并证实合理时间内用紫外可见区特定波长光照铁卟啉蛋白可引发其氧化还原反应，光激发卟啉到其电子激发态，改变卟啉的电离势和电子亲和能，反应过程中伴随着铁卟啉能量/电子转移和激发态中间体的产生等，但目前尚未清晰理解完整的光反应分子机制。因此本课题选取肌红蛋白和细胞色素c等铁卟啉蛋白，实验上运用激光闪光光解监测铁卟啉分子激发态Sn在衰减过程中的动态变化，运用气体在线质谱和电子顺磁共振技术等确定光反应中间体等；理论上运用DFT/TD-DFT、Marcus电子转移理论和QM/MM等理解光激发铁卟啉蛋白分子内从电子供体到电子受体的能量/电子转移过程和后续的光化学反应过程。在已取得的前期工作基础上，得到以下主要研究成果：.1、确定氨基酸（游离氨基酸、蛋白内氨基酸）、小分子（O2，H2O等）对光激发铁卟啉蛋白反应过程的影响，总结光激发过程中光谱特点及规律，确定反应中电子供体与受体，在较多典型实验与理论分析的基础上，找出此类蛋白氧化还原的机制。.2、光激发电子受体/供体及反应中间体的确定。从谱学实验和量化方法结合确定，从而可进一步分析光化学反应过程及电子行为。.3、光激发蛋白铁卟啉反应电子传递过程和最低能量途径。需要激光闪光光解、在线质谱、时间分辨荧光等实验方法，结合理论中的过渡态理论和Marcus电子转移理论等理解电子传递反应的动力学和热力学过程，理解蛋白环境下分析蛋白内铁卟啉电子转移与能量转移情况。.4、在国内外重要学术期刊上发表论文16篇，其中SCI、EI收录论文12篇；申请专利2项。.5、培养博士研究生1名，培养硕士研究生18名，培养青年教师3名。