The 2.0 A structure of malarial purine phosphoribosyltransferase in complex with a transition-state analogue inhibitor.
The 2.0 A structure of malarial purine phosphoribosyltransferase in complex with a transition-state analogue inhibitor.
复制标题
疟疾嘌呤磷酸核糖基转移酶与过渡态类似物抑制剂复合物的 2.0 A 结构。
DOI：
10.1021/bi990664p
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Almo,SC
中科院分区：
文献类型：
--
作者：
Shi,W;Li,CM;Tyler,PC;Furneaux,RH;Cahill,SM;Girvin,ME;Grubmeyer,C;Schramm,VL;Almo,SC
疟疾是全世界因传染病死亡的主要原因。恶性疟原虫在人红细胞中的增殖需要通过次黄嘌呤-鸟嘌呤-黄嘌呤磷酸化核糖转移酶（HGXPRTase）来回收嘌呤。这种酶是开发新型抗疟药的靶标。过渡态类似物抑制剂的设计和合成允许与疟疾酶共结晶，并将配合物细化到2.0 Å分辨率。疟疾酶的催化位点接触与人类次黄嘌呤-鸟嘌呤磷酸核糖基转移酶（HGPRTase）相似，尽管底物特异性不同。结合抑制剂、焦磷酸盐和两个Mg2+离子的疟疾HGXPRTase的晶体结构揭示了过渡态类似物的独特特征。底物辅助催化发生在O5 '孤对和焦磷酸氧的核氧羰基稳定化。一个离解反应的配位路径涉及主要的反应配位运动是核糖体C1 '在相对不移动的嘌呤碱和（Mg）2−焦磷酸之间的运动。在酶和抑制剂的复合物中形成几个短氢键。疟疾HGXPRTase过渡态类似物的质子核磁共振谱在14.3和15.3 ppm时包含两个下场信号。尽管这些配合物的结构与人类的酶相似，但核磁共振光谱揭示了人类和疟疾HG(X)PRTases的过渡态类似物之间氢键的差异。x射线晶体结构和核磁共振光谱揭示了化学和结构特征，为设计疟疾特异性过渡态抑制剂提供了一种策略。
Malaria is a leading cause of worldwide mortality from infectious disease.Plasmodium falciparumproliferation in human erythrocytes requires purine salvage by hypoxanthine−guanine−xanthine phosphoribosyltransferase (HGXPRTase). The enzyme is a target for the development of novel antimalarials. Design and synthesis of transition-state analogue inhibitors permitted cocrystallization with the malarial enzyme and refinement of the complex to 2.0 Å resolution. Catalytic site contacts in the malarial enzyme are similar to those of human hypoxanthine−guanine phosphoribosyltransferase (HGPRTase) despite distinct substrate specificity. The crystal structure of malarial HGXPRTase with bound inhibitor, pyrophosphate, and two Mg2+ions reveals features unique to the transition-state analogue complex. Substrate-assisted catalysis occurs by ribooxocarbenium stabilization from the O5‘ lone pair and a pyrophosphate oxygen. A dissociative reaction coordinate path is implicated in which the primary reaction coordinate motion is the ribosyl C1‘ in motion between relatively immobile purine base and (Mg)2−pyrophosphate. Several short hydrogen bonds form in the complex of the enzyme and inhibitor. The proton NMR spectrum of the transition-state analogue complex of malarial HGXPRTase contains two downfield signals at 14.3 and 15.3 ppm. Despite the structural similarity to the human enzyme, the NMR spectra of the complexes reveal differences in hydrogen bonding between the transition-state analogue complexes of the human and malarial HG(X)PRTases. The X-ray crystal structures and NMR spectra reveal chemical and structural features that suggest a strategy for the design of malaria-specific transition-state inhibitors.