紫外光谱法研究久效磷与碱基的相互作用

摘要

为利用组合化学原理构建核酸适体库，确定久效磷适体筛选缓冲体系的最适 pH 值及离子强度，采用紫外吸收光谱法研究了不同 pH 值及不同 Na ﹢、K ﹢和 Mg2﹢浓度的缓冲溶液中久效磷与四种碱基的相互作用。结果表明，pH 值及 Na ﹢、K ﹢和 Mg2﹢浓度对久效磷与四种碱基的作用有明显的影响，pH7.6、Na ﹢浓度200 mmol/ L、K ﹢浓度40 mmol/ L、Mg2﹢浓度15 mmol/ L 的50 mmol/ L Tris 缓冲溶液中久效磷与四种碱基的作用相对较强，可以作为久效磷适体筛选的参考缓冲体系。在此缓冲体系下，久效磷与四种碱基作用的强弱依次为胞嘧啶、胸腺嘧啶、腺嘌呤、鸟嘌呤。因此，构建核酸适体库时可以适当增加胞嘧啶、胸腺嘧啶的比例。%In order to construct aptamer library using principles of combinatorial chemistry and determine pH and ionic strength of buffer when selecting monocrotophos aptamer,the interaction between monocrotophos and four bases including thymine,cytosine,adenine and guanine were studied by means of ultraviolet absorption spectrum in different pH values and concentration of Na﹢, K﹢ and Mg2﹢. The results showed that effect of pH values and concentration of Na﹢, K﹢ and Mg2﹢on interaction between monocrotophos and four bases was apparent,espe-cially at pH7.6, the concentration of 200 mmol/L Na﹢, 40mmol/L K﹢ and 15mmol/L Mg2﹢, the buffer could be used to select aptamer of monocrotophos. In the buffer system,the sequence of interaction between monocro-tophos and four bases was adenine,cytosine,thymine,guanine. So the ratio of cytosine and thymine can be in-creased when aptamer library will be constructed.