Baranauskienė Lina, Matulis Daumantas
Department of Biothermodynamics and Drug Design, Vilnius University Institute of Biotechnology, Graičiūno 8, Vilnius LT-02241, Lithuania.
BMC Biophys. 2012 Jun 7;5:12. doi: 10.1186/2046-1682-5-12.
Human carbonic anhydrases (CAs) play crucial role in various physiological processes including carbon dioxide and hydrocarbon transport, acid homeostasis, biosynthetic reactions, and various pathological processes, especially tumor progression. Therefore, CAs are interesting targets for pharmaceutical research. The structure-activity relationships (SAR) of designed inhibitors require detailed thermodynamic and structural characterization of the binding reaction. Unfortunately, most publications list only the observed thermodynamic parameters that are significantly different from the intrinsic parameters. However, only intrinsic parameters could be used in the rational design and SAR of the novel compounds.
Intrinsic binding parameters for several inhibitors, including ethoxzolamide, trifluoromethanesulfonamide, and acetazolamide, binding to recombinant human CA XIII isozyme were determined. The parameters were the intrinsic Gibbs free energy, enthalpy, entropy, and the heat capacity. They were determined by titration calorimetry and thermal shift assay in a wide pH and temperature range to dissect all linked protonation reaction contributions.
Precise determination of the inhibitor binding thermodynamics enabled correct intrinsic affinity and enthalpy ranking of the compounds and provided the means for SAR analysis of other rationally designed CA inhibitors.
人类碳酸酐酶（CAs）在包括二氧化碳和碳氢化合物运输、酸碱平衡、生物合成反应以及各种病理过程（尤其是肿瘤进展）等多种生理过程中发挥着关键作用。因此，碳酸酐酶是药物研究的有趣靶点。设计抑制剂的构效关系（SAR）需要对结合反应进行详细的热力学和结构表征。不幸的是，大多数出版物仅列出了与内在参数有显著差异的观测热力学参数。然而，只有内在参数可用于新型化合物的合理设计和构效关系研究。
测定了几种抑制剂（包括乙氧唑胺、三氟甲磺酰胺和乙酰唑胺）与重组人CA XIII同工酶结合的内在结合参数。这些参数包括内在吉布斯自由能、焓、熵和热容。通过在较宽的pH和温度范围内进行滴定热分析和热位移分析来确定这些参数，以剖析所有相关的质子化反应贡献。
抑制剂结合热力学的精确测定能够对化合物进行正确的内在亲和力和焓排序，并为其他合理设计的CA抑制剂的构效关系分析提供了方法。
