【摘要】 黄精凝集素Ⅱ (PolygonatumcyrtonemaHua .LectinⅡ ,PCLⅡ )具有 32 3nm的荧光发射峰和 2 81.6nm的激发峰 .其远紫外圆二色谱 (CD谱 )显示 2 2 4nm负峰 ,分子中含 17.3%的α螺旋和 4 5.8%的 β折叠 .在 10mmol/L的SDS中 ,PCLⅡ完全丧失兔红细胞凝集能力及促T 淋巴细胞有丝分裂活性 ,CD谱呈现双负峰的α螺旋构象 ;去除SDS后 ,则呈无规卷曲构象 .此时 ,荧光发射峰红移而激发峰蓝移 ,PCLⅡ仍完全失活 .在EDTANa2 溶液中 ,PCLⅡ凝集红细胞能力及促淋巴细胞有丝分裂活性完全丧失 ;去除EDTA后 ,红细胞凝集活性完全恢复 ,但仍失去促淋巴细胞有丝分裂能力 .PCLⅡ二级结构变化不大 ,荧光光谱的变化表明微环境受到影响更多还原

【Abstract】 To demonstrate the roles of Ca 2+ 、Mg 2+ in the conformation and function of Polygonatum cyrtonema Hua. lectin Ⅱ (abbev. PCLⅡ), the conformational changeof PCLⅡ was studied by fluorescence and circular dichroism (CD) spectra. Intrinsic fluorescence of PCLⅡ showed the λ max of emission and excitation spectrum at 323nm and 281.6nm respectively, it indicated that tryptophan was in a hydrophobic microenvironment. The relative fluorescence intensity excitated at 281.6nm was bigger than that at 295nm so far, so the energy was transfered from tyrosin to tryptophan. The far ultraviolet (UV) CD spectra exhibited a rare negative peak with minimum at 224nm and two negative shoulders at 212nm and 234nm, While its near UV CD spectra showed negative peak at 278nm and shoulders at 260nm、285nm、300nm. It contains about 17.3% α helix and 45.8% β sheet. In 10mmol/L sodium dodecyl sulphate(SDS), the near UV CD spectra disappeared, while far UV CD spectra showed a typical double negative peaks between 200～225nm, removed with excess SDS, the near-UV spectra centered at 278nm regained partly, but at far UV region, it exhibited a random coil curve. The λ max of fluorescence emission spectra red shifted to 331nm. but excitation spectra blue shifted to 279nm, the relative fluorescence intensity all increased about 70%, PCLⅡ lost activity as hemagglutination and mitogen towards T cell completely. Treated with disodium ethylene diamine tetracetate(EDTANa 2), PCLⅡ lost activity as mentioned, the negative shoulder at 212nm disappeared, while the peak and shoulder of near UV region at 278nm and 300nm red shifted, and a new shoulder appeared at 275nm. Removing EDTANa 2, the new shoulder at 275nm disappeared, λ max of emission and excitation spectra were all blue shifted with the increased relative fluorescence intensity, PCLⅡ left hemagglutination activity intact, but lost mitogenic activity towards T cell, so at least there were two functional domain in PCLⅡ to start various reaction, EDTANa 2 could inhibite the hemagglutination of PCLⅡ. Maybe Ca 2+ , Mg 2+ were need for PCLⅡ to maintain special micro environment conformation to trigger serial signal and result the division of T cell, but not essential for hemagglutination.更多还原