Effect of Amino Acid Residue and Oligosaccharide Chain Chemical Modifications on Spectral and Hemagglutinating Activity of Millettia dielsiana Harms. ex Diels. Lectin

编号 zgly0000369810

文献类型 期刊论文

文献题名 Effect of Amino Acid Residue and Oligosaccharide Chain Chemical Modifications on Spectral and Hemagglutinating Activity of Millettia dielsiana Harms. ex Diels. Lectin

作者 ShunGAO  JieAN  Chuan-FangWU  YingGU  FangCHEN  YuanYU  Qia-QingWU  Jin-KuBAO 

作者单位 CollegeofLifeSciences  ChengduInstituteofBiology 

母体文献 Acta Biochinica et Biophysica Sinica;生物化学与生物物理学报: 英文版 

年卷期 2005,37(1)

页码 47-54

年份 2005 

分类号 Q946.1 

关键词 氨基酸残基  血凝集反应  鸡血藤  植物凝集素  低聚糖  化学修饰  圆形二色性  荧光猝灭光谱 

文摘内容 The effects of modifying the carbohydrate chain and amino acids on the conformation and activity of Millettia dielsiana Harms. ex Diels. lectin (MDL) were studied by hemagglutination, fluorescence and circular dichroism analysis. The modification of tryptophan residues led to a compete loss of hemagglutinating activity; however, the addition of mannose was able to prevent this loss of activity. The results indicate that two tryptophan residues are involved in the carbohydrate-binding site. Modifications of the carboxyl group residues produced an 80% loss of activity, but the presence of mannose protected against the modification. The results suggest that the carboxyl groups of aspartic and glutamic acids are involved in the carbohydrate-binding site of the lectin. However, oxidation of the carbohydrate chain and modification of the histidine and arginine residues did not affect the hemagglutinating activity of MDL. Fluorescence studies of MDL indicate that tryptophan residues are present in a relatively hydrophobic region, and the binding of mannose to MDL could quench tryptophan fluorescence without any change in λmax. The circular dichroism spectrum showed that all of these modifications affected the conformation of the MDL molecule to different extents, except the modification of arginine residues. Fluorescence quenching showed that acrylamide and iodoacetic acids are able to quench 77% and 98% of the fluorescence of tryptophan in MDL, respectively. However, KI produced a barely perceptible effect on the fluorescence of MDL, even when the concentration of I^- was 0.15M. This demonstrates that most of tryptophan residues are located in relatively hydrophobic or negatively charged areas near the surface of the MDL molecule。