游离氨基酸调控光致铁卟啉蛋白氧化还原反应研究

The iron-porphyrin proteins undertake various functions inside animals. Since the iron-porphyrin is buried deeply in the proteins consisting of hundreds of amino acids, the light irradiated redox reaction of iron-porphyrin proteins, as well as effects of free amino acids were neglected in most researches. Inspired by the excellent optical and electrical performances of the structure analog chlorophyll in plants, we found the photo irradiation could influence the processes of redox reaction of iron-porphyrin proteins significantly. Since free amino acids and radicals could get close to the iron-porphyrin, we proved they can regulate the photo excited redox reaction of iron-porphyrin proteins via suitable photo irradiation. In this project diversified spectroscopy methods and computational quantum chemistry methods will be utilized to investigate the orientation of free tryptophan and cysteine on photo excited redox reaction of iron-porphyrin proteins. The ultraviolet and visible light irradiated reaction of iron porphyrin proteins will be tracked in free amino acids solutions with different spectroscopy approaches. The decay dynamics of tryptophan intermediates and porphyrin excited states will then be measured and the intermediates will be assigned accordingly. Experiments are also designed to inspect the offering electron process from sulfhydryl group of cysteine to excited state porphyrin, and to comprehend the assistance of gas in regulating the photo-excited iron-porphyrin reaction. Computational quantum chemistry and molecular dynamics are applied to clarify the above process to further validate the reaction mechanistic assumptions. All experiments of the photo excited reaction of iron-porphyrin proteins are carried out under physiological conditions. Our research results can be applied to meat preservation for better retaining the freshness and color under ambient conditions without any harmful chemical additives, thus has significant application value for diet and health securities of human beings.

动物体内铁卟啉类蛋白承担着多种功能，铁卟啉深藏于由大量氨基酸组成的蛋白内部，多数研究基本不考虑其光激发条件下氧化还原反应问题，更忽略了游离氨基酸作用。受结构相似、具有优异光电特性的叶绿素启发，我们发现光照可显著影响铁卟啉氧化还原反应。由于游离氨基酸及其自由基易接近铁卟啉，在合理光照和溶液条件下，可调控光致铁卟啉蛋白氧化还原反应！本课题将研究色氨酸和半胱氨酸对光致该类蛋白氧化/还原反应调控情况。光谱实验确定紫外和可见光激发氨基酸溶液中此类蛋白反应，检测色氨酸中间体和激发态卟啉衰减动力学过程，并归属反应中间体；考察半胱氨酸巯基为激发态铁卟啉提供电子过程和气体协助调控光激发蛋白氧化还原反应情况；结合量化计算和分子动力学等协助理解以上过程及推测反应路径。本课题在生理条件下研究氨基酸调控光致铁卟啉蛋白反应，可应用于肉类保鲜保色过程中，避免使用有害化学添加剂，对人类饮食安全和自身健康具有重大应用价值。

受结构相似、具有优异光电特性的叶绿素启发，本课题开展了光照诱导调控蛋白内铁卟啉氧化还原反应研究。研究发现了游离氨基酸在合理光照和溶液条件下，可调控光致铁卟啉蛋白氧化还原反应。本课题研究了色氨酸等氨基酸对光致铁卟啉的蛋白氧化/还原反应调控情况，通过光谱实验确定了紫外和可见光激发色氨酸和半胱氨酸溶液中铁卟啉蛋白反应；检测了中间体和激发态卟啉衰减动力学过程，并归属反应中间体，推测其反应机理。本论文采用密度泛函和含时密度泛函方法研究了针对母核结构修饰所得到的新卟啉分子，结果表明杂原子和Zn配位明显改变了卟啉类分子的光吸收性质。使用分子动力学模拟的方法研究了胰高血糖素样肽-1与胰高血糖素样肽-1受体胞外区域的相互作用,研究了空载的N端细胞外结构域（ECD）以及GLP-1结合状态下的ECD，从分子水平上理解二者的相互作用。本课题根据其光照铁卟啉还原原理，可应用于肉类保鲜保色过程中，对鲜肉储存运输具有重大应用价值。