BIOLOGICALLY-IMPORTANT FURANOSYL RINGS

生物重要呋喃类化合物(即溶液)的几种性质 开环和合环的组成、构象和动力学 将研究反应(互变异构化)。实验方法 涉及：a.呋喃糖和呋喃糖结构变体的合成 所有环构型中的磷酸盐允许结构功能 比较。化合物将被稳定的同位素(13C，2H)标记到 便于通过高场核磁共振光谱学进行检查。 B.互变异构体的鉴定和定量 用核磁共振测定呋喃糖水溶液，并特别注意 形成了羰基和水合物。 C.三键1H-1H的测量和构象解释， 13C-1H和13C-13C耦合常数与自旋-晶格(T1)弛豫 呋喃糖环中的(13C，1H)倍。放松研究将涉及 用沙漠和动态NOE核磁共振方法获得绝对1H-1H 核间距离，将从该距离评估构象。 将由核磁共振推导出的优选环构象与 由MO计算预测。 D.单向速率常数的测量和解释 用核磁共振研究呋喃糖互变异构化。将测量激活参数 对于每个组分的反应。 简单呋喃类化合物的溶液研究将扩展到 核糖核苷和寡核苷酸。几种富含GC的化合物 寡核苷酸，其碱基序列与在 大肠杆菌tRNAglu的茎，将被制备成含有 全氢呋喃核糖残基的核磁共振研究 解决方案结构。 建议的研究是追求更长远目标的先决条件。 目的确定结合特异性的分子基础 核酸和蛋白质之间的关系，以及糖的作用 代谢调节中的互变异构化。

Several properties of biologically-important furanoses (i.e., solution composition and conformation, and kinetics of ring-opening and ring-closing reactions (tautomerization) will be studied. The experimental approach involves: A. Synthesis of structural variants of furanoses and furanose phosphates in all ring configurations to permit structure-function comparisons. Compounds will be labeled with stable isotopes (13C, 2H) to facilitate examination by high-field NMR spectroscopy. B. Identification and quantitation of the tautomeric forms present in aqueous solutions of furanoses by NMR, with particular attention given to carbonyl and hydrate forms. C. Measurement and conformational interpretation of three-bond 1H-1H, 13C-1H and 13C-13C coupling constants and spin-lattice (T1) relaxation times (13C, 1H) in furanosyl rings. Relaxation studies will involve the use of DESERT and dynamic NOE NMR methods to obtain absolute 1H-1H internuclear distances, from which conformation will be assessed. Preferred ring conformations deduced by NMR will be compared to those predicted by MO calculations. D. Measurement and interpretation of unidirectional rate constants of furanose tautomerization by NMR. Activation parameters will be measured for each component reaction. Solution studies of simple furanoses will be extended to the ribonucleosides and oligoribonucleotides. Several GC-rich oligoribonucleotides, having base sequences identical to those found in the stems of E. coli tRNAglu, will be prepared containing perdeutero-ribofuranosyl residues to facilitate NMR studies of their solution structures. The proposed studies are a prerequisite to the pursuit of the longer-term objective of determining the molecular basis for the binding specificity between nucleic acids and proteins, and on elucidating the effect of sugar tautomerization on metabolic regulation.