In this paper,the fluorescence dynamics of tryptophan residues in LicT protein is investigated by time-resolved fluorescence method combined with UV absorption and steady-state fluorescence spectroscopy.The local microenvironment and structural changes of LicT protein before and after activation are studied.The activated LicT protein AC 141 prevents the antitermination of gene transcription involved in carbohydrate utilization to accelerate the body's metabolism.The structural properties and microenvironment of activated protein AC 141 and wild-type protein Q 22 were determined by different fluorescence emissions and lifetimes of tryptophan residues.The interaction between tryptophan residues and solvent is elucidated by decay associated spectroscopy (DAS) and time-resolved emission spectra (TRES),indicating that upon activation,the structure of AC 141 is more compact than that of wild-type Q 22.In addition,TRES also showed that tryptophan residues in the protein had a continuous spectral relaxation process.Anisotropy results illustrated the conformational motions of residues and whole proteins,suggesting that tryptophan residues had independent local motions in the protein system,and that the motions were more intense in the activated protein.%使用时间分辨荧光方法,结合紫外吸收光谱和稳态荧光光谱技术,测量了LicT蛋白中色氨酸残基的荧光动力学特性,进而对LicT蛋白质激活前后的局部微环境和结构变化进行了研究.LicT蛋白质的激活态使得有关糖类利用的基因转录过程继续进行,促进机体新陈代谢.通过色氨酸残基的荧光发射和寿命的差异判断出激活型蛋白AC 141和野生型蛋白Q 22不同的结构性质和微环境差异.在此基础上,通过衰减相关光谱(DAS)和时间分辨发射光谱(TRES)阐释了两种蛋白色氨酸残基和溶剂的相互作用,说明了激活型AC 141的比野生型Q 22的结构更加紧密.此外,TRES还说明了蛋白中的色氨酸残基存在连续光谱弛豫过程.各向异性结果则对残基和整个蛋白的构象运动进行了阐述,说明了色氨酸残基在蛋白质体系内有独立的局部运动,且在激活型蛋白中该运动更加强烈.
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