Probes for Studies of Nucleotide-Binding Proteins

描述(申请人提供)：该项目致力于通过合成和物理化学评价来开发一类新型的跨糖苷链5‘-核苷酸。一种单一的通用合成策略已经被开发出来，用于任何感兴趣的5‘-核苷酸的系链。它被成功地用来制备前两个系链的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，这种新的系链的特殊性质及其与核苷酸框架的结合方式使5‘-核苷酸生物模拟达到了前所未有的程度。在所有实际用途中，系留的5‘-核苷酸在化学上与它们的天然对应核苷酸相同，但仅限于一组有限的空间构象。进一步的研究将证实它们高度仿生的特性，并展示它们在生物医学研究中的用途。合成各种精心选择的目标，并通过核磁共振光谱和X射线结晶学进行广泛的表征，是这项工作要开展的具体活动。 构象限制可以产生有价值的蛋白质-配体结构-功能关系的探针。只有两个键旋转决定了5‘-核苷酸的大部分分子形貌：C4’-C5‘键和糖苷键(嘧啶类化合物为C1’-N1，嘌呤类化合物为C1‘-N9)，而这些都同时受到新的系链的限制。跨糖核苷酸连接基序的理想特征包括限制反构象中的糖苷键，保留杂环苷元的生物识别关键氢键位置，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骨架的设计。该提案中的拴系基序符合所有这些标准，未来对拴系靶的使用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.