黄牛肝菌凝集素的化学修饰与荧光光谱研究
Chemical modification and fluorescence analysis of lectin from ？？Boletus fulvus

对黄牛肝菌凝集素(？？Boletus fulvus？？ lectin, BFL)进行氨基酸化学修饰, 结果表明, Trp残基、Tyr残基及Ser/Thr残基的修饰都会对BFL的凝血活性产生影响, 表明这些残基是BFL凝血活性所必需的, 可能参与了其凝血活性中心的构成. 而Arg残基修饰后, BFL的凝血活性未发生改变, 表明Arg不是维持BFL凝血活性的必需基团. 内源荧光光谱分析结果表明, BFL所发射的荧光是由Trp残基贡献的, 且Trp残基在BFL分子中所处的微环境极性较弱, 屏蔽于一定的构象当中. 温度、pH值及变性剂对BFL内源荧光光谱的影响与基本理化性质的实验结果一致. 氨基酸修饰对荧光光谱的影响表明, Trp残基修饰会引起BFL？仍从？光光谱较大变动, 而Tyr、Ser/Thr残基修饰对BFL？仍从？光光谱影响不大.
Chemical modification of amino acid residues of ？？Boletus fulvus？？ lectin (BFL) showed that treating purified BFL with amino acid modifying reagents specific for Trp, Tyr and Ser/Thr could affect the hemagglutination activity of BFL. These results indicated that these residues played important roles in the hemagglutination activity of BFL, and might be essential for constituting the active center of BFL, whereas Arg might not be essential for constituting the active center of BFL. Moreover, the fluorescence spectrum of native BFL suggested that Trp residues made great contribution to the fluorescence of BFL, and they might locate in the hydrophobic microenvironment of BFL and be buried in the hydrophobic core of the lectin. The influences of temperature, pH and denaturants on the fluorescence spectrum of BFL were consistent with the hemagglutination assays. The experiment of amino acid modification suggested that modification of Trp significantly affected the fluorescence spectrum of BFL, whereas modification of Tyr and Ser/Thr induced little change on the fluorescence spectrum of BFL