【摘要】 采用圆二色谱、荧光光谱,研究了黄精凝集素II(PolygonatumcyrtonemaHua.LectinII,PCLII)在4mol/L和6mol/L盐酸胍中,以及巯基修饰后,其活性和分子构象的变化关系.研究结果表明:PCLII是一种稳定的蛋白质,巯基修饰剂虽不影响其活性,但可使其分子构象发生变化,去除修饰剂后其结构部分能够恢复.在4mol/L盐酸胍中,PCLII活性及构象可发生很大变化,去除盐酸胍后其活性恢复;在6mol/L盐酸胍中,呈现典型的无规卷曲构象,活性完全丧失,去除盐酸胍后活性仍不能恢复,表明活性中心已遭到不可逆的破坏.更多还原

【Abstract】 To demonstrate the relationship between conformation and biological activity ofPolyonatum cyrtonemaHua.Lectin II (PCL II), denaturant and thiol group reagents were used to modify PCL II, and the conformational change of PCL II was studied by fluorescence and circular dichroism (CD) spectra. In 4mol/L and 6mol/L guanidine hydrochloride, the λmax of fluorescence emission spectra redshifted and the relative fluorescence intensity decreased obviously. In 4mol/L guanidine hydrochloride, the nearUV CD spectra peak and shoulders disappeared, the of 256nm shoulder increase remarkable.At farUV region, a negative peak appeared at 242nm, the peak of 224nm and shoulder of 236nm disappeared, the shoulder of 208nm turned into a negative peak. Removed excess guanidine hydrochloride, the nearUV CD spectra centered at 260～320nm regained partly. In 6mol/L guanidine hydrochloride, the shoulder and peak of farUV region disappeared, the shoulder of 256nm in nearUV region redshifted to 260nm, and became a positive peak, Removed excess guanidine hydrochloride, the UV CD regained, but the biological activity lost. The results showed that the conformation of activity center was destroyed unreversely. Modification of hydrosulfide group, the nearUV and farUV CD spectra had little changed, but theλmax of fluorescence emission spectra redshifted and the relative fluorescence intensity decreased obviously, especially themodified by DTT and PCMB. 更多还原