IN SEARCH OF THE UNIVERSAL NUCLEIC ACID BASE

用作通用核酸碱基的修饰核苷 将被合成，它们是否适合作为 物理化学和分子水平上确定的寡核苷酸探针 生物学研究。候选结构包括 2-carbamoyl-4-beta-D-deoxyribofuranosylimidazole， 5-carbamoyl-3-beta-D-deoxyribofuranosyl-1，2，4-triazole，和 6-氨基-4-嘧啶酮通过三个原子间隔连接到脱氧核糖上 C-5和C-L。这些化合物被设计成通过两个氢进行碱基配对 与da、dc、dg或t的键。四倍简并度由下式获得 构造分子，其中两个键的独立旋转是 足以改变碱基位置和氢键给体和受体 网站。拟进行的具体研究包括：1) 核苷将被合成并结合到寡核苷酸中，方法是 标准亚磷酸盐化学方法。2)熔化曲线和 含该基团的典型寡核苷酸的热力学性质 万能基地将被确定。3)万能基础能力 修饰低聚物在杂交检测中的作用 低水平的信使核糖核酸将被确定。4)含低聚物 通用基地还将评估他们作为 测序引物，作为聚合酶链式反应(PCR)中的引物。5) 最后，将进行实验，以确定寡核苷酸是否 其中含有修饰的碱基可用作现场定向的模板 诱变。很明显，一个普遍的基础将具有广泛和 直接应用于生物化学和分子生物学。它对以下方面的影响 分子遗传学和生物医学研究可能是深远的。

Modified nucleosides designed to function as universal nucleic acid bases will be synthesized and their suitability as constituents of oligonucleotide probes determined in physicochemical and molecular biological studies. The candidate structures include 2-carbamoyl-4-beta-D-deoxyribofuranosylimidazole, 5-carbamoyl-3-beta-D-deoxyribofuranosyl-1,2,4-triazole, and 6-amino-4-pyrimidone linked to deoxyribose via three atom spacers between C-5 and C-l'. The compounds are designed to base-pair through two hydrogen bonds to dA, dC, dG, or T. The four-fold degeneracy is obtained by constructing molecules wherein independent rotation of two bonds is sufficient to shift both base position and hydrogen bond donor and acceptor sites. The specific studies to be pursued include the following: 1) The nucleosides will be synthesized and incorporated into oligonucleotides by way of standard phosphoramidite chemistry. 2) The melting curves and thermodynamic properties of representative oligonucleotides containing the universal bases will be determined. 3) The ability of universal base modified oligomers to function in hybridization assays for the detection of low levels of mRNA will be determined. 4) Oligomers containing the universal base will also be assessed for their ability to serve as sequencing primers, as primers in the polymerase chain reaction (PCR). 5) Finally, experiments will be done to determine whether oligonucleotides which contain the modified bases can be used as templates for site-directed mutagenesis. It is clear that a universal base would have extensive and direct application to biochemistry and molecular biology. Its impact on molecular genetics, and biomedical research could be profound.