A method of analysing a nucleic acid by mass spectrometry comprising the steps of: (1) preparing a nucleic acid molecule comprising a negatively charged non-phosphate sugar-sugar linkage; (2) eliminating the charge from all, or up to all but ten, of the sugar-sugar linkages of the said nucleic acid molecule; (3) introducing the said nucleic acid molecule in which the charge has been wholly or partly eliminated as said into a mass spectrometer, and (4) determining the mass of the said nucleic acid molecule. Preferably, the nucleic acid has no or one charge. A method of preparing a nucleic acid molecule containing no or up to ten negative charges and no or up to ten positive charges comprising the steps of (1) synthesising a nucleic acid with a phosphorothioate linkage or a phosphoroselenoate linkage between sugar residues, and (2) reacting the said nucleic acid with an alkylating agent so as to eliminate the charge on the said phosphorothioate linkage or said phosphoroselenoate linkage. The methods are useful for DNA sequencing and mutation analysis, and the nucleic acids are useful to suppress gene expression.
一种利用质谱分析核酸的方法,包括以下步骤(1) 制备包含带负电荷的非
磷酸糖-糖连接的核酸分子;(2) 从所述核酸分子的全部或最多不超过 10 个糖-糖连接中消除电荷;(3) 将已如上所述全部或部分消除电荷的所述核酸分子引入质谱仪,以及 (4) 确定所述核酸分子的质量。核酸最好不带电荷或只带一种电荷。一种制备不含或最多含 10 个负电荷和不含或最多含 10 个正电荷的核酸分子的方法,包括以下步骤:(1) 合成糖残基之间具有
硫代磷酸酯连接或亚
硒酸磷酸酯连接的核酸;(2) 使所述核酸与烷化剂反应,以消除所述
硫代磷酸酯连接或亚
硒酸磷酸酯连接上的电荷。这些方法可用于 DNA 测序和突变分析,核酸可用于抑制
基因表达。