The introduction of potassium-competitive acid blockers (P-CABs) has been a major innovation in gastric H,K-ATPase inhibition and many laboratories are actively engaged in the development of novel molecules within this class. This work investigates the interaction between H,K-ATPase and tegoprazan, a representative of the P-CABs group, in terms of K+ and H+ binding, through functional and structural analyses. First, by studying the H,K-ATPase activity we found a model to describe the non-Michaelis Menten kinetics through a "ping-pong" mechanism that explains a stoichiometry of 1 H+, 1 K+, and 1 ATP molecule, but also considering the influence of H+ on the ionization states of the protein. A kinetic evaluation of the inhibition of tegoprazan denotes the binding to two different intermediates states with apparent Kd (μM) 0.56 ± 0.04 and 2.70 ± 0.24 at pH 7.2. Molecular dynamics simulations revealed important changes in the interactions of tegoprazan with the transmembrane residues depending on whether the site contains K+ or not. This explains the decrease in affinity as a function of K+ concentration observed in the kinetic experiments. On the other hand, the structures predict that the protonation of tegoprazan is responsible for the change in its dihedral angle. The rotation of the benzimidazole ring allows the inhibitor to be positioned further into the luminal cavity, a situation compatible with the higher inhibition affinity of H,K-ATPase measured at low pH. Results presented herein will provide a basis for the rational design of novel P-CABs ligands.

中文翻译：

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配体如何调节胃 H，K-ATP 酶活性及其被 TEGOPRAZAN 抑制。


钾竞争性酸阻滞剂 （P-CAB） 的引入是胃 H，K-ATP 酶抑制的重大创新，许多实验室正在积极参与此类新分子的开发。这项工作通过功能和结构分析研究了 H，K-ATP 酶与 P-CABs 组的代表 tegoprazan 在 K+ 和 H+ 结合方面的相互作用。首先，通过研究 H，K-ATP 酶活性，我们找到了一个模型，通过“乒乓”机制描述非 Michaelis Menten 动力学，该机制解释了 1 H+、1 K+ 和 1 个 ATP 分子的化学计量，但也考虑了 H+ 对蛋白质电离态的影响。替戈拉赞抑制的动力学评价表示在 pH 值为 7.2 时，与两种不同中间体状态的结合，表观 Kd （μM） 分别为 0.56 ± 0.04 和 2.70 ± 0.24。分子动力学模拟揭示了替戈拉赞与跨膜残基相互作用的重要变化，具体取决于该位点是否含有 K + 。这解释了在动力学实验中观察到的亲和力随 K+ 浓度的函数而降低。另一方面，这些结构预测 tegoprazan 的质子化是导致其二面角变化的原因。苯并咪唑环的旋转使抑制剂能够进一步定位到管腔中，这种情况与在低 pH 值下测得的 H，K-ATP 酶的较高抑制亲和力相符。本文介绍的结果将为新型 P-CABs 配体的合理设计提供基础。