【摘要】 用圆二色谱研究了天花粉蛋白在酸性和碱性溶液中的构象,并观察了在十二烷基磺酸钠(SDS)溶液中天花粉蛋白分子构象的变化,用Chen,Yang与Martinez等人的方法计算了各种条件下天花粉蛋白二级结构含量.结果表明:在很宽广的pH范围内(从pH2到pH12)分子构象基本上是稳定的.但是,在强碱性条件下即pH>12(室温)或pH11.5(40℃)螺旋含量显著减少.在碱性条件下,于250nm附近出现一新的CD带,它的强度与离解的酪氨酸残基个数呈线性关系,说明这一新带主要是由离解的酪氨酸残基产生的.更多还原

【Abstract】 The conformation of Trichosanthin in acidic solution and alkaline solution has been investigated by circular dichroism. The conformational change of this protein molecule in the presence of SDS (sodium dodecyl sulfate) has also been studied. The contents of α helix and β-sheet in various experimental conditions were calculated according to the method of Chen, Yang and Martines. The Secondary structure of Trichosanthin is Stable within wide pH range (from pH 2 to pH 12), but in very alkaline solution, namely pH>12 (room temperature) or pH>11.5 (40℃), the content of α-helix decreases obviously.At alkaline pH a newly generated band appears at around 250nm. An approximately linear relation is obtained between the value of (θ) at the maximun of the CD band around 250 nm and the number of ionized tyrosyl residues. Obviously the band is attributed to the ionized tyrosin.更多还原