镧离子对酵母tRNA圆二色谱的影响

Effects of Lanthanum(Ⅲ) Ions on Circular Dichroism Spectrum of Yeast tRNA

采用圆二色谱（ＣＤ）方法对镧离子（Ｌａ３＋）与转移核糖核酸（ｔＲＮＡ）的相互作用进行了研究．结果显示Ｌａ３＋可使酵母ｔＲＮＡ的ＣＤ谱峰向短波方向偏移３ｎｍ，波峰位于２５４ｎｍ，峰值减少１０％，说明结合在ｔＲＮＡ分子上的Ｌａ３＋引起ｔＲＮＡ分子构象的变化．Ｌａ３＋对氨酰化ｔＲＮＡ合成酶（ａａＲＳ）或ｔＲＮＡ－ａａＲＳ复合物的ＣＤ光谱基本上无影响，说明Ｌａ３＋对氨酰化反应活性的影响。

The interaction of Lanthanum(Ⅲ) ion(La^3+) with yeast tRNA was studied by circular dichroism(CD) spectrum.The results show that the peak position of yeast tRNA was slightly shifted towards short wavelength by 3 nm in the presence of 2 μmol/L La^3+,iefrom 257-254 nm;and the amplitude of positive peak at 254 nm was decreased by about 10%.The conformational change of yeast tRNA was caused by the binding of La^3+ to tRNA.La3+ did not change the CD spectra of either yeast aminoacyltRNA synthetase(aaRS) or tRNAaaRS complex,which suggests that the effects of La^3+ on the aminoacylation reaction activity may mainly be due to the conformational change of tRNA. 