氨基酸修饰及荧光光谱分析研究黄花石蒜凝集素生物学活性与构象的关系

Studies on the Chemical Modification of Amino Acids Residues and Fluorescence Spectrum of Lycoris aurea Agglutinin

本文通过对黄花石蒜凝集素(Lycoris aurea Agglutinin,LAA)进行特殊氨基酸的化学修饰,显示一个LAA分子一共有8个色氨酸分子,其中有3个位于分子表面或近表面,Trp、Tyr和Ser/Thr不是LAA凝集活性所必需的氨基酸,而Asp/Glu的羧基和凝血活性密切相关,对其修饰后导致凝血活性丧失50%。通过荧光淬灭的方法对LAA分子中色氨酸所处微环境进行了研究。结果显示中性淬灭剂丙烯酰胺对LAA分子中色氨酸的淬灭作用最强可以淬灭100%的色氨酸荧光,其次是离子型淬灭剂碘化钾,能淬灭62.9%的色氨酸荧光,而氯化铯对LAA色氨酸的淬灭最弱,几乎不能淬灭LAA的荧光。

Chemical modification studies on Lycoris aurea Agglutinin （LAA） demonstrated that LAA contains 8 Trp residues, among which about 3 Trp residues located the surface of protein and can be modified. Asp/Glu residues were essential for the hemagglutinating activity of LAA. However, chemical modification of Trp, Tyr and Ser/Thr didn＇t affect the hemagglutinating activity of LAA. Fluorescence quenching study was carried out with three quenchers. Maximum quenching was observed with acrylamide,followed by iodide,quenching about 100% and 62.9% fluorescence of LAA, respectively. However, CsCl can not quench the intrinsic fluorescence of Trp residues.