钕和镧离子对tRNA圆二色谱的影响

EFFECTS OF NEODYMIUM ION AND LANTHANUM ION ON CIRCULAR DICHROISM OF tRNA

采用圆二色谱方法对钕和镧离子与转移核糖核酸间的相互作用进行了研究，结果显示在１．５～６μｍｏｌ／ＬＮｄ３＋或Ｌａ３＋离子存在下，ｔＲＮＡ分子ＣＤ谱２６０ｎｍ（＋）峰蓝移２～３ｎｍ，２６０ｎｍ（＋）峰值分别增加６％和２０％左右；２１０ｎｍ（－）峰在不同摩尔比Ｎｄ３＋／ｔＲＮＡ作用下，谱峰蓝移或红移，峰值增加或降低５０％左右。结果说明结合在ｔＲＮＡ分子上的Ｎｄ３＋或Ｌａ３＋可能引起ｔＲＮＡ分子构象的变化。Ｅｕ３＋对大肠杆菌ＬｅｕＲＳ或ｔＲＮＡＬｅｕ－ＬｅｕＲＳ复合物的ＣＤ谱具有一定的影响。

The interaction of neodymium ion (Nd 3+ ) and lanthanum ion (La 3+ ) with tRNA was studied by circular dichroism (CD) spectrum. The result showed that the peak 260 nm(+) was slightly blue shifted by 2￣3 nm in the presence of 1.5￣6 μmol/L Nd 3+ or La 3+ and the amplitude of 260 nm(+) peak was increased by about 6% and 20% for Nd 3+ and La 3+ respectively. The peak 210 nm(-) blue or red shifted at difference molar ratio of Nd 3+ /tRNA for the native tRNA and Mg 2+ free tRNA. The amplitude of the peak 210 nm(-) was increased or decreased by about 50%. These results indicated that the conformational change of tRNA was caused by the binding of Nd 3+ and La 3+ to tRNA. Eu 3+ had some effect on the CD spectra of Escherichia coli Leucyl tRNA Synthetase (LeuRS) and tRNA LeuRS complex. 〖WT5”HZ]