【摘要】 玉竹凝集素(POL)的最大荧光发射峰位于328 nm处,比游离色氨酸(Trp)的最大荧光发射峰(348 nm)蓝移了近20 nm,说明Trp周围的极性较弱,处于疏水的微环境。化学修饰表明色氨酸和酪氨酸与其凝集活性无关。羧基的修饰导致活性降低60%,表明Asp/Glu是构成其凝血活性中心的必需氨基酸或是位于活性中心附近。二硫键的修饰使其活性丧失,表明二硫键是维持其活性中心的关键化学键。Lys残基的修饰凝血活性降低40%,表明该残基与其活性中心相关。组氨酸残基的专一性修饰导致凝血活性的完全丧失,表明组氨酸是构成其凝血活性中心的必需氨基酸。更多还原

【Abstract】 The fluorescence spectrum （FLS） of POL exicted at 280 nm and 295 nm showed a maximum peak at 328 nm, and the fluorescence energy of Tyr was transformed to Trp and strengthened the fluorescence of Trp. The λ_max of fluorescence emission spectrum blue-shifted about 20 nm compared with the λ_max of free Tyr（348 nm）. Modification of tyr and trp residues had no effect on its hemagglutinating activity. Treated the -S-S- and -SH with DTT and NEM respectively resulted in the hemagglutination activity of POL totally inactivated. Modification of carboxyl groups with EDC led to a 60% drop in POL activity. Treating the purified POL with DEPC an affinity-modifying reagent specific for histidine totally inactivated the lectin with modification of histidine residues. Modification of Lys residues with TNBS led to a 40% drop in POL activity.更多还原