Stromelysin inhibitors designed from weakly bound fragments: Effects of linking and cooperativity
Stromelysin inhibitors designed from weakly bound fragments: Effects of linking and cooperativity
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DOI：
10.1021/ja9702780
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发表时间：
1997-06-25
影响因子：
15
通讯作者：
Fesik, SW
中科院分区：
文献类型：
--
作者：
Olejniczak, ET;Hajduk, PJ;Fesik, SW
在之前的文章中，(1)我们报道了一种强效的基质金属蛋白酶基质溶酶非肽抑制剂的发现，这种抑制剂是通过连接两个与蛋白质相邻位点弱结合的配体制备的。在这里，我们用等温滴定量热法描述了焓和熵对观察到的键合和非键合化合物结合能的贡献。基于核磁共振衍生的基质溶素/抑制剂复合物结构，对量热实验结果进行了解释。此外，还进行了酶动力学分析，以测量非拴配体的协同结合。对于非拴系化合物，乙酰羟肟酸的存在使联芳基配体的结合能增加了1.3千卡/摩尔。这种能量的增加在本质上是自由的，可以部分归因于两个配体之间的直接色散相互作用。对于连接的化合物，焓对结合能的贡献严重依赖于连接体长度，而熵的贡献几乎没有依赖关系。通过二亚甲基桥连接羟基甲酸酯和联芳基的化合物的焓显著增加，由于联芳基部分在结合袋中的位置不同，对于具有较长连接物的化合物没有观察到。这种差异破坏了配体和蛋白质之间的关键相互作用，并突出了连接体在栓系化合物设计中的重要性。
In the preceding paper,(1) we reported on the discovery of potent, nonpeptide inhibitors of the matrix metalloproteinase stromelysin that were prepared by linking two ligands which bind weakly to adjacent sites on the protein. Here we describe the enthalpic and entropic contributions to the observed binding energy for both the linked and unlinked compounds using isothermal titration calorimetry. The results of the calorimetric experiments were interpreted on the basis of NMR-derived structures of stromelysin/inhibitor complexes. In addition, enzyme kinetic assays were performed to measure the cooperative binding of the untethered ligands. For the untethered compounds, the presence of acetohydroxamic acid increases the binding energy of biaryl ligands by similar to 1.3 kcal/mol. This gain in energy is enthalpic in nature and can be attributed, in part, to a direct dispersion interaction between the two ligands. For the linked compounds, enthalpic contributions to the binding energy depend critically on the linker length, whereas the entropic contributions show virtually no dependence. The significant gains in enthalpy observed for a compound which linked the hydroxamate to the biaryl with a two methylene bridge was not observed for compounds with longer linkers due to a difference in the position of the biaryl moiety in the binding pocket. This difference disrupts key interactions between the ligand and the protein and highlights the importance of the linker in the design of tethered compounds.