【摘要】 由天花粉蛋白的水和重水溶液的激光拉曼光谱,测得酰胺Ⅲ谱带1240cm^-1和酰胺I谱带1632,1660cm^-1对CH₂弯曲模式1448cm^-1的强度比值。按Lippert等建立的方程组作定量计算,求得天花粉蛋白的二级结构含量为α-螺旋43.5％,β-折叠31.3％和无序25.2％,它们与4 分辨率天花粉蛋白单晶X射线衍射法的结果相一致。同时,研究了上述溶液的冻干粉状固体的二级结构,经过冻干,使其中约10％的β-折叠转变成无序构象,而α-螺旋含量无明显变化。在水溶液中,由测得的I₈₅₀/I₈₃₀比值计算,天花粉蛋白中的酪氨酸残基约有80％呈“暴露式”。更多还原

【Abstract】 The Raman spectral intensities of trichosanthin at the conformation sensitive frequency 1240 cm^-1 in H₂O （amide Ⅲ） and 1632cm^-1 and 1660 cm^-1 in D₂O （amide Ⅰ） relative to the intensity of 14480m^-1 methylene band was measured. The secondary structural content of trichosanthin was calculated according to the method developed by Lippert et al: 43.5％ for α-helix, 31.3％ for β-sheet and 25.2％ for disordered. Those values are in agreement with the results of X-ray crystal analysis of 4 resolution. Lyophilized poweder of the above trichosanthin solution are measured by the same method. It indicates that about 10％ β-sheet was changed to the disordered conformation and α-helix content remains unchanged.In aqueous solution, quantitative treatment of Raman data proved that about 80％ tyrosine residues are "exposed".更多还原