• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >THERMODYNAMIC MAPPING OF THE INHIBITOR SITE OF THE ASPARTIC PROTEASE ENDOTHIAPEPSIN
【24h】

THERMODYNAMIC MAPPING OF THE INHIBITOR SITE OF THE ASPARTIC PROTEASE ENDOTHIAPEPSIN

机译：天冬氨酸蛋白酶内毒素的抑制剂位点的热力学映射

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The discovery that the protease from the human immunodeficiency virus (HIV) belongs to the aspartic protease family has generated renewed interest in this class of proteins. In this paper, the interactions of endothiapepsin, an aspartic proteinase from the fungus Endothia parasitica, with the inhibitor pepstatin A have been studied by high-sensitivity calorimetric techniques. These experiments have permitted a complete characterization of the temperature and pH-dependence of the binding energetics. The binding reaction is characterized by negative intrinsic binding enthalpy and negative heat capacity changes. The association constant is maximal at low pH (2 x 10(9) M(-1) at pH 3) but decreases upon increasing pH (8.1 x 10(6) M(-1) at pH 7). The binding of the inhibitor is coupled to the protonation of one of the aspartic moieties in the Asp dyad of the catalytic site of the protein. This phenomenon is responsible for the decrease in the apparent affinity of the inhibitor for the enzyme upon increasing pH. The experimental results presented here indicate that the binding of the inhibitor is favored both enthalpically and entropically. While the favorable enthalpic contribution is intuitively expected, the favorable entropic contribution is due to the large gain in solvent-related entropy associated with the burial of a large hydrophobic surface, that overcompensates the loss in conformational and translational/rotational degrees of freedom upon complex formation. The characteristics of the molecular recognition process have been evaluated by means of structure-based thermodynamic analysis. Three regions in the protein contribute significantly to the free energy of binding: the residues surrounding the Asp dyad (Asp32 in the N-terminal lobe and Asp215 in the C-terminal domain) and the flap region (Il73 to Asp77). In addition, the rearrangement of residues that are not in immediate contact with the inhibitor provides close to 40% of the protease contribution to the binding free energy. On the other hand, the two statine residues provide more than half of the inhibitor contributions to the total free energy of binding. It is demonstrated that a previously developed empirical structural parametrization of the thermodynamic parameters that define the Gibbs energy, accurately accounts for the binding energetics and its temperature and pH-dependence. [References: 49]
机译：来自人类免疫缺陷病毒（HIV）的蛋白酶属于天冬氨酸蛋白酶家族的发现引起了人们对该类蛋白质的新兴趣。在本文中，已通过高灵敏度量热技术研究了寄生于真菌寄生性内皮素的天冬氨酸蛋白酶内皮抑素与抑制剂抑肽酶A的相互作用。这些实验已经完全表征了结合能的温度和pH依赖性。结合反应的特征在于负的固有结合焓和负的热容变化。缔合常数在低pH值（pH 3时为2 x 10（9）M（-1））下最大，但在增加pH值时（pH 7时为8.1 x 10（6）M（-1）时降低。抑制剂的结合与蛋白质催化位点的Asp二聚体中的天冬氨酸部分之一的质子化偶联。这种现象是由于pH升高导致抑制剂对酶的表观亲和力下降的原因。此处给出的实验结果表明，抑制剂的结合在焓和熵上都得到了促进。尽管可以直观地预期到有利的焓贡献，但是有利的熵贡献是由于与溶剂相关的熵的大量增加与大疏水表面的掩埋相关，这过度补偿了复合物形成时构象和平移/旋转自由度的损失。分子识别过程的特征已通过基于结构的热力学分析进行了评估。蛋白质中的三个区域显着促进了结合的自由能：Asp二聚体周围的残基（N端叶中的Asp32和C端域中的Asp215）和襟翼区域（Il73至Asp77）。另外，不与抑制剂直接接触的残基的重排提供了蛋白酶对结合自由能的近40％的贡献。另一方面，两个他汀类药物残基提供了抑制剂总结合自由能的一半以上。结果表明，先前定义的热力学参数的经验结构参数化定义了吉布斯能量，准确地说明了结合能及其温度和pH依赖性。 [参考：49]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号