色氨酸阻遏物与其操纵基因复合物的圆二色性研究  

CIRCULAR DICHROISM SPECTRA OF TRP REPRESSOR COMPLEXED WITH ITS SYNTHETIC OPERATOR

作　　者：崔涛[1] 戴文煊 刘蔚[1] 

机构地区：[1]中国科学技术大学生物系,合肥230026

出　　处：《生物物理学报》1993年第4期523-528,共6页Acta Biophysica Sinica

基　　金：中国科学院青年基金资助

摘　　要：用圆二色性谱来研究色氨酸阻遏物与其操纵基因复合物在溶液中的构象变化.色氨酸阻遏物的圆二色性图谱表明它是一种富含X螺旋的蛋白质.通过比较加入L-Trp前和后的圆二色性谱,发现活性的与非活性的色氨酸阻遏物二级结构变化很小,trp PO的圆二色性谱与它的单键、双链理论计算曲线对比,可近似推测操纵基因在溶液中的存在状态.用色氨酸阻遏物对trp PO进行确定,可以从中找出蛋白质与核酸结合的平衡点.从平衡时蛋白质-核酸复合物标准圆二色性谱与游离状态色氨酸阻遏物乘以比例因子的圆二色谱的比较,得出形成复合物后的色氨酸阻遏物的二级结构变化很小.The conformational changes of tip repressor complexed with its synthetic operator was studied by means of circular dichroism (CD) spectra. Results showed that trp repressor is a α -helix rich protein. The CD spectra with and without L-Trp implied that there are a little difference between the secondary structure of aporepressor and repressor. The conformation of trp P/O was contrasted the CD spectra of trp P/O with that of the calculated curves. The titration of trp P'O was linear up to a break point at a [nucleotide]/[trp repressor] ratio of 1.67 in trp repressor titration. By comparing CD spectra of the repressor-operator with its calculated curve, it showed that the secondary structure of trp repressor curves changed a little while it was complexed with a synthetic operator.

关 键 词：圆二色性 色氨酸 阻遏物 操纵基因 

分 类 号：Q71[生物学—分子生物学]