Probes for Studies of Nucleotide-Binding Proteins

描述（由申请人提供）：该项目的重点是通过合成和理化评价开发一类新型的转糖苷键连接的5 '-核苷酸。已经开发了用于拴系任何感兴趣的5 '-核苷酸的单一通用合成策略。它成功地用于制备前两个拴系的5 '-核苷酸靶标。根据蛋白质数据库中蛋白质结合配体的构象配置，这种新系链的特定性质及其与核苷酸框架的连接模式允许前所未有程度的5 '-核苷酸仿生。拴系的5 '-核苷酸对于所有实际目的而言与它们的天然对应物化学上相同，但限于有限的空间构象集合。进一步的发展将证实其高度仿生的功能，并证明其实用性的生物医学研究。合成各种精心挑选的目标，并通过NMR光谱和X射线晶体学进行广泛的表征是这项工作中要进行的具体活动。 构象限制可以产生蛋白质-配体结构-功能关系的有价值的探针。只有两个键旋转决定了5 '-核苷酸的大部分分子拓扑结构：C4'-C5'键和糖苷键（嘧啶的C1'-N1和嘌呤的C1 '-N9），并且它们同时受到新系链的限制。转糖苷核苷酸系链基序的理想特征包括限制反构象中的糖苷键、保留杂环糖苷配基的生物降解关键氢键合位点、保留可官能化的碳水化合物羟基以及可用于嘧啶和嘌呤核苷框架的设计。该提案中的拴系基序符合所有这些标准，未来使用拴系靶标可能有助于理解许多生物化学上重要的5 '-核苷酸结合蛋白的构象/结合/功能关系。

DESCRIPTION (provided by applicant): This project focuses on the development of a novel class of transglycosidically tethered 5'-nucleotides by synthesis and physicochemical evaluation. A single general synthetic strategy for the tethering of any 5'-nucleotide of interest has already been developed. It was used successfully to prepare the first two tethered 5'-nucleotide targets. The specific nature of this new tether and its mode of attachment to a nucleotide framework allow an unprecedented degree of 5'-nucleotide biomimicry according to the conformational disposition of the protein-bound ligands in the Protein Data Bank. The tethered 5'-nucleotides are for all practical purposes chemically identical to their natural counterparts but are restricted to a limited set of spatial conformations. Further development will confirm their highly biomimetic features and demonstrate their utility to biomedical investigations. Synthesis of a variety of carefully selected targets, and extensive characterization by NMR spectroscopy and X-ray crystallography are the specific activities to be undertaken in this work. Conformational restriction can generate valuable probes of protein-ligand structure-function relationships. Just two bond rotations determine most of the molecular topography of 5'-nucleotides: the C4'-C5' bond and the glycosidic one (C1'-N1 for pyrimidines and C1'-N9 for purines), and these are restricted simultaneously by the new tether. The desirable features of a transglycosidic nucleotide-tethering motif include restriction of the glycosidic bond in an anti conformation, preservation of the biorecognition-critical hydrogen bonding sites of the heterocyclic aglycon, retention of the functionalizable carbohydrate hydroxyl groups, and a design that can be used on both the pyrimidine and the purine nucleoside frameworks. The tethering motif featured in this proposal meets all these criteria, and future use of the tethered targets could contribute to an understanding of conformation/binding/function relationships in many biochemically important 5'-nucleotide-binding proteins.