EXPLORANDO O MECANISMO DE DEGRADAÇÃO ENZIMÁTICA DO POLIURETANO (PU) POR MEIO DAS POLIURETANASES ESTERASES A E B (PueA E PueB): UMA ABORDAGEM INTEGRADA DE DOCKING, DINÂMICA MOLECULAR (MD) E QM/MM

Abstract

The continuous global production of polyurethane (PU) and its environmental persistence generate negative impacts on ecosystems, driving the search for sustainable handling solutions, specifically the use of enzymes. Therefore, this study seeks to elucidate the understanding of the enzymatic degradation mechanism of polyurethanase esterases A and B (PueA and PueB) applied to PU-MDI (methylene diphenyl diisocyanate). In this sense, previously built structures were used and dockings were carried out for the PueA and PueB complexes. The results indicate binding scores of -10.743 and -9.587 kcal mol-1 for PueA and PueB, respectively. Furthermore, the complexes were then subjected to molecular dynamics simulations (MD) for 500 ns in triplicate, showing a good interaction between the enzymes and the PU-MDI. Finally, a QM/MM (quantum mechanics/molecular mechanics) simulation, starting with an adequate snapshot from classical MD was carried out, and a relaxed scan was performed to obtain the occurrence coordinates, followed by umbrella sampling to obtain the free energy profile of the systems. The results indicate that the PueA and PueB reaction mechanisms occur in two steps, with determining energy barriers of 11.95 and 15.10 kcal mol-1, respectively, indicating that these enzymes may be used to degrade PU.