Transition State Analysis of Diphtheria Toxin

描述(申请人提供)：ADP-核糖化细菌外毒素是 导致各种严重人类疾病的蛋白质，如 霍乱、咳嗽和白喉。白喉毒素(DT)催化 NAD+的ADPriBosyl基团与双乙酰胺残基的共价转移 真核细胞伸长因子2(EEF-2)。这种共价转移会失活 EEF-2，使其不能延长多肽链，抑制 蛋白质合成，最终杀死目标细胞。的目标是 这项建议是为了确定过渡状态结构 动态同位素法研究白喉毒素对EEF-2的ADP-核糖基化作用 放射性标记NAD+类似物的效应(KIE)。分子的过渡态分析 由白喉毒素催化的反应将得到更好的结果。 对这种酶的了解，并应为 设计新型过渡态类似物作为缓蚀剂。

DESCRIPTION (provided by applicant): ADP-ribosylating bacterial exotoxins are proteins that are responsible for various severe human diseases such as cholera, pretussis, and diphtheria. Diphtheria toxin (DT) catalyzes the covalent transfer of the ADPribosyl moiety of NAD+ to a dipthamide residue in eukaryotic elongation factor 2 (eEF-2). This covalent transfer inactivates eEF-2, rendering it incapable of polypeptide chain elongation, inhibiting protein synthesis and eventually killing the target cells. The objective of this proposal is to determine the transition state structure of ADP-ribosylation of eEF-2 by diphtheria toxin by measuring kinetic isotope effects (KIEs) with radiolabeled NAD+ analogues. Transition state analysis of the reaction catalyzed by diphtheria toxin will result in a better understanding of this enzyme and should provide target structures for the design of novel transition state analogues as inhibitors.