条斑紫菜凝集素的化学修饰

为探索条斑紫菜凝集素(Porphyra yezoensis Ueda Lectin PYL)的作用机理,对纯化的条斑紫菜凝集素分子进行化学修饰,测定与其活性相关的氨基酸残基。结果表明,经碘乙酸、NEM、DTT修饰后的PYL,其凝集活性均未发生任何改变,表明分子中的自由巯基、二硫键与凝集活性无关。PYL经NEM修饰,有2.6个分子表面的自由-SH被修饰。在5mmol.L-1的NAI下,PYL凝集活性不变,但在10、20mmol.L-1 NAI时凝集活性分别丧失50%,75%,经羟胺处理后恢复部分活性,说明Tyr和氨基在PYL的凝集活性中起一定的作用;Glu和Asp的化学修饰,其凝集活性丧失93.75%,说明酸性氨基酸谷氨酸和天冬氨酸是PYL凝集活性的重要组成部分。

Chemical modification of lectin from Porphyra yezoensis

The purified Porphyra yezoensis Ueda Lectin （PYL） was studied with various chemical modifications to detect the a mino acid residues involved in the hemagglutinating activity. The chemical modification of PYL with IAA, NEM,DTT,induced not any obvious changes on hemagglutinating activity. It showed that free - SH, disul- fide bonds of the molecular had no relation with the hemagglutinating activity of PYL. Modified --SH with NEM. There were 2. 6 free --SH in surface of PYL. The hemagglutination of PYL also kept no change when modified by 5 mmol · L-1 NAI, but modification of PYL with10 and 20 mmol · L-1 NAI was accompanied by a loss of 50 % and 75 % of hemagglutination activity respectively. PYL modified by hydroxyla mine still resumed partial hemagglutination activity, The Tyr and - NH2 played certainly role in hemagglutination activity. Modifi- cation of gluta mine and asparagine was accompanied by a loss of 93. 75 % of hemagglutination activity , which indicated that the acidity amino acid （gluta mine and asparagine） were the important parts of PYL‘’s hemaggluti- nation activity.