Chang C, Lee C G
Biochemistry. 1981 Apr 28;20(9):2657-61. doi: 10.1021/bi00512a046.
Direct study of the methylation of ribonucleic acid with methyl methanesulfonate by carbon-13 nuclear magnetic resonance spectroscopy has demonstrated the usefulness of this method in studying the chemical modification of biomacro-molecules and the interaction between nucleic acids and biologically active agents. This direct stable isotope method eliminated all tedious and questionable degradation processes for determining the reactive sites and the product distributions. Six methylated products, 7-methylguanosine, 1-methyladenosine, 3-methylcytidine, 1-methylguanosine, 3-methyluridine, and methyl phosphodiester, were identified by comparison with many model compounds and careful examination of spin-spin coupling and spin-lattice relaxation time. An extensive study of the interaction of phosphate buffer with methyl methansulfonate accounted for the sharp difference in the 13C spectra of the methylated RNA isolated from the reactions controlled by a pH-stat and phosphate buffer, respectively. The 13C-enriched agent significantly enhances the specificity and sensitivity of the method and provides better quantitative results.
通过碳-13核磁共振光谱法直接研究核糖核酸与甲磺酸甲酯的甲基化反应，证明了该方法在研究生物大分子的化学修饰以及核酸与生物活性剂之间相互作用方面的有效性。这种直接稳定同位素方法消除了所有用于确定反应位点和产物分布的繁琐且有问题的降解过程。通过与许多模型化合物进行比较，并仔细检查自旋-自旋耦合和自旋-晶格弛豫时间，鉴定出了六种甲基化产物，即7-甲基鸟苷、1-甲基腺苷、3-甲基胞苷、1-甲基鸟苷、3-甲基尿苷和甲基磷酸二酯。对磷酸盐缓冲液与甲磺酸甲酯相互作用的广泛研究解释了分别由pH计和磷酸盐缓冲液控制反应所分离得到的甲基化RNA的13C光谱中的显著差异。富含13C的试剂显著提高了该方法的特异性和灵敏度，并提供了更好的定量结果。
