RESUMO

Endosulfan is an organochlorine insecticide widely used for agricultural pest control. Many nations worldwide have restricted or completely banned it due to its extreme toxicity to fish and aquatic invertebrates. Arthrobacter sp. strain KW has the ability to degrade α, ß endosulfan and its intermediate metabolite endosulfate; this degradation is associated with Ese protein, a two-component flavin-dependent monooxygenase (TC-FDM). Employing in silico tools, we obtained the 3D model of Ese protein, and our results suggest that it belongs to the Luciferase Like Monooxygenase family (LLM). Docking studies showed that the residues V59, V315, D316, and T335 interact with α-endosulfan. The residues: V59, T60, V315, D316, and T335 are implicated in the interacting site with ß-endosulfan, and the residues: H17, V315, D316, T335, N364, and Q363 participate in the interaction with endosulfate. Topological analysis of the electron density by means of the Quantum Theory of Atoms in Molecules (QTAIM) and the Non-Covalent Interaction (NCI) index reveals that the Ese-ligands complexes are formed mainly by dispersive forces, where Cl atoms have a predominant role. As Ese is a monooxygenase member, we predict the homodimer formation. However, enzymatic studies must be developed to investigate the Ese protein's enzymatic and catalytic activity.

Assuntos

Arthrobacter , Inseticidas , Animais , Endossulfano/química , Endossulfano/metabolismo , Arthrobacter/metabolismo , Biodegradação Ambiental , Inseticidas/química , Inseticidas/metabolismo , Oxigenases de Função Mista

RESUMO

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerged coronavirus responsible for coronavirus disease 2019 (COVID-19); it become a pandemic since March 2020. To date, there have been described three lineages of SARS-CoV-2 circulating worldwide, two of them are found among Mexican population, within these, we observed three mutations of spike (S) protein located at amino acids H49Y, D614G, and T573I. To understand if these mutations could affect the structural behavior of S protein of SARS-CoV-2, as well as the binding with S protein inhibitors (cepharanthine, nelfinavir, and hydroxychloroquine), molecular dynamic simulations and molecular docking were employed. It was found that these punctual mutations affect considerably the structural behavior of the S protein compared to wild type, which also affect the binding of its inhibitors into their respective binding site. Thus, further experimental studies are needed to explore if these affectations have an impact on drug-S protein binding and its possible clinical effect.

Assuntos

COVID-19/virologia , Mutação Puntual , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética , Sequência de Aminoácidos , COVID-19/epidemiologia , Descoberta de Drogas , Humanos , Ligantes , México/epidemiologia , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Conformação Proteica , SARS-CoV-2/química , Alinhamento de Sequência , Glicoproteína da Espícula de Coronavírus/química

RESUMO

CO is extremely toxic to humans since it can combine with haemoglobin to form carboxy-haemoglobin that reduces the oxygen-carrying capacity of blood. Metal-organic frameworks (MOFs), in particular InOF-1, are currently receiving preferential attention for the separation and capture of CO. In this investigation we report a theoretical study based on periodic density-functional-theory (DFT) analysis and matching experimental results (in situ DRIFTS). The aim of this article is to describe the non-covalent interactions between the functional groups of InOF-1 and the CO molecule since they are crucial to understand the adsorption mechanism of these materials. Our results show that the CO molecule mainly interacts with the µ2-OH hydroxo groups of InOF-1 through O-HO hydrogen bonds, and Cπ interactions by the biphenyl rings of the MOF. These results provide useful information on the CO adsorption mechanisms in InOF-1.

RESUMO

The confinement of small amounts of benzene in InOF-1 (Bz@InOF-1) shows a contradictory behavior in the capture of CO2 and SO2. While the capture of CO2 is increased 1.6 times, compared to the pristine material, the capture of SO2 shows a considerable decrease. To elucidate these behaviors, the interactions of CO2 and SO2 with Bz@InOF-1 were studied by DFT periodical calculations postulating a plausible explanation: (a) in the case of benzene and CO2, these molecules do not compete for the preferential adsorption sites within InOF-1, providing a cooperative CO2 capture enhancement and (b) benzene and SO2 strongly compete for these preferential adsorption sites inside the MOF material, reducing the total SO2 capture.

RESUMO

The enhancement of CO2 capture due to the confinement of polar molecules within InOF-1 was previously demonstrated. In particular, the presence of MeOH produced 1.30-fold increase in the total CO2 capture. This was explained before with the presence of hydrogen bonds. However, a detailed analysis of the hydrogen bonds among µ2-OH functional groups, MeOH molecules and CO2 molecules was not elucidated; moreover, the possible mechanisms that could explain the enhancement of the capture were also not explained. In this investigation, the density functional theory (DFT) periodic calculations and experimental in situ DRIFTS results allowed us to postulate four plausible CO2 adsorption mechanisms for MeOH-functionalised InOF-1, which described the hydrogen bonds and rationalised the nature of the CO2 capture enhancement.

RESUMO

The 2-propanol (i-PrOH) adsorption properties of InOF-1 are investigated along with the confinement of small amounts of this alcohol to enhance the CO2 capture for i-PrOH@InOF-1 (1.25-fold improvement compared to pristine InOF-1). InOF-1 exhibited a high affinity towards i-PrOH, experimentally quantified by ΔHads (-55 kJ mol-1), and DFT geometry optimisations showed strong hydrogen bonding between O(i-PrOH) and H(µ2-OH). Quantum chemical models demonstrated that the CO2 capture increase for i-PrOH@InOF-1 was due to a decrease in the void surface of InOF-1 (bottleneck effect), and the formation of essential hydrogen bonds of CO2 with i-PrOH and with the hydroxo functional group (µ2-OH) of InOF-1.

RESUMO

In this work we present a detailed analysis of selected reaction schemes in terms of the atomic components of the electronic energy defined by the quantum theory of atoms in molecules and the interacting quantum atoms method. The aim is to provide an interpretation tool for the energy change involved in a chemical reaction by means of the atomic and interaction contributions to the energies of the molecules involved. Ring strain in cyclic alkanes, the resonance energy of aromatic and antiaromatic molecules, local aromaticity in polycyclic aromatic hydrocarbons, intermolecular bonding in hydrogen fluoride clusters, and hydration of d-block metal dications were selected for the study. It was found that in addition to the changes in the strong C-C interactions in the carbon skeleton of the organic molecular rings, other contributions not usually considered to be important such as those between C and H atoms (either bonded or not) need to be considered in order to account for the net energy changes. The analysis unveils the role of the ionic and covalent contributions to the hydrogen bonding in HF clusters and the energetic origin and extent of cooperative effects involved. Moreover, the "double-hump" behavior observed for the hydration energy trend of [M(H2O)6]2+ complexes is explained in terms of the deformation energy of the metal cation and the increasingly covalent metal-water interactions. In addition, proper comparisons with the description provided by other methodologies are briefly discussed. The topological approach proposed in this contribution proves to be useful for the description of energy changes of apposite reaction schemes in chemically meaningful terms.