The electrostatic potential surface maps generated for the amino acid–DRV complexes investigated the extent of interactions within the active site of the protein. This analysis of the molecular orbitals allowed us to explore the nature of the interactions present between active site amino acids and the DRV in native and mutated proteins. Molecular orbitals HOMO and LUMO noted down upon the M06–2X/6–31G(d,p) level optimized amino acid–DRV geometries helped us explain which region of the inhibitor has the ability to interact with the amino acid more effectively. Quantum chemical calculations have been performed at the M06–2X/6–31G(d,p) level of theory to investigate the strength and nature of interactions between the active site amino acids at positions 25 and 30 with darunavir (DRV) inhibitor of two native (D25 and D30 in 4L元, 1T3R) and five mutant (N25 in 3BVB, 3SO9 N30 in 2F80, 3LZV, 3UCB) HIV–1 proteases. The results will provide a new way to study the catalytic hydrolysis of CS 2. During the hydrolysis of CS 2, the six reaction paths are parallel and competitive. It was found that the hydrolysis of CS 2 was an exothermic reaction, and the increase in temperature was unfavorable to the reaction.

Besides, to further explain which reaction path is better, the hydrolysis kinetics of CS 2 was analyzed. Also, to further explore the reaction of CS 2 hydrolysis, the natural bond orbital (NBO) analysis of the transition states was carried out. Similarly, the order of the barriers for the three paths in the second reaction is C=S path < C=S path and C=O path < C=O path. In the first step of the reaction, the rate-determining step in both the single C=S path and the double C=S path has a higher barrier of 199.9 kJ/mol, but the 127.9 kJ/mol barrier in the double C=S path has a lower barrier of 142.8 kJ/mol in the single C=S path. Therefore, hydrogen migration is crucial to the mechanism of CS 2 hydrolysis. By optimizing the structure of reactants, intermediates, transition states, and products, the conclusion shows that the first step of CS 2 (CS 2 reacts with H 2 O first to form COS intermediate) The second step (COS intermediate reacts with H 2 O to form H 2 S and CO 2 ). Density functional theory (DFT) is used to investigate the two-step hydrolysis mechanism of CS 2.

Whas the supplementary angle of 142.8