The extensive spread of COVID-19 in every continent shows that SARS-CoV-2 virus has a higher transmission rate than SARS-CoV virus which emerged in 2002. This results in a global pandemic that is difficult to control. In this investigation, we analyze the interaction of N3 inhibitor and the main protease of SARS-CoV and SARS-CoV-2 by quantum chemistry calculations. Non-covalent interactions involved in these systems were studied using a model of 469 atoms. Density Functional Theory and Quantum Theory of Atoms in Molecules calculations lead us to the conclusion that non-conventional hydrogen bonds are important to describe attractive interactions in these complexes. The energy of these non-conventional hydrogen bonds represents more than a half of the estimated interaction energy for non-covalent contacts. This means that hydrogen bonds are crucial to correctly describe the bonds between inhibitors and the main proteases. These results could be useful for the design of new drugs, since non-covalent interactions are related to possible mechanisms of action of molecules used against these viruses.

COVID-19在各大洲的广泛传播表明，SARS-CoV-2病毒的传播率高于2002年出现的SARS-CoV病毒。这导致全球大流行难以控制。在这项调查中，我们通过量子化学计算分析了 N3 抑制剂与 SARS-CoV 和 SARS-CoV-2 的主要蛋白酶的相互作用。使用 469 个原子的模型研究了这些系统中涉及的非共价相互作用。分子计算中原子的密度泛函理论和量子理论使我们得出结论，非常规氢键对于描述这些复合物中的吸引力相互作用很重要。这些非常规氢键的能量代表了非共价接触估计相互作用能的一半以上。这意味着氢键对于正确描述抑制剂和主要蛋白酶之间的键至关重要。这些结果可能有助于设计新药，因为非共价相互作用与用于对抗这些病毒的分子的可能作用机制有关。