Quantum biochemical analysis of the TtgR regulator and effectors.

The recent expansion of multidrug-resistant (MDR) pathogens poses significant challenges in treating healthcare-associated infections. Although antibacterial resistance occurs by numerous mechanisms, active efflux of the drugs is a critical concern. A single species of efflux pump can produce a simultaneous resistance to several drugs. One of the best-studied efflux pumps is the TtgABC: a tripartite resistance-nodulation-division (RND) efflux pump implicated in the intrinsic antibiotic resistance in Pseudomonas putida DOT-T1E. The expression of the TtgABC gene is down-regulated by the HTH-type transcriptional repressor TtgR. In this context, by employing quantum chemistry methods based on the Density Functional Theory (DFT) within the Molecular Fragmentation with Conjugate Caps (MFCC) approach, we investigate the coupling profiles of the transcriptional regulator TtgR in complex with quercetin (QUE), a natural polyphenolic flavonoid, tetracycline (TAC), and chloramphenicol (CLM), two broad-spectrum antimicrobial agents. Our quantum biochemical computational results show the: [i] convergence radius, [ii] total binding energy, [iii] relevance (energetically) of the ligands regions, and [iv] most relevant amino acids residues of the TtgR-QUE/TAC/CLM complexes, pointing out distinctions and similarities among them. These findings improve the understanding of the binding mechanism of effectors and facilitate the development of new chemicals targeting TtgR, helping in the battle against the rise of resistance to antimicrobial drugs. These advances are crucial in the ongoing fight against rising antimicrobial drug resistance, providing hope for a future where healthcare-associated infections can be more beneficially treated.

Quantum Biochemical Investigation of Lys49-PLA2 from Bothrops moojeni.

Envenomation via snakebites occurs largely in areas where it is harder to access the hospital. Its mortality rate and sequelae acquired by the survivors symbolize a big challenge for antivenom therapy. In particular, the homologous phospholipase A2 (Lys49-PLA2) proteins can induce myonecrosis and are not effectively neutralized by current treatments. Thus, by taking advantage of crystallographic structures of Bothrops moojeni Lys49-PLA2 complexed with VRD (varespladib) and AIN (aspirin), a quantum biochemistry study based on the molecular fractionation with conjugate cap scheme within the density functional theory formalism is performed to unveil these complexes' detailed interaction energies. The calculations revealed that important interactions between ligands and the Lys49-PLA2 pocket could occur up to a pocket radius of r = 6.5 (5.0 Å) for VRD (AIN), with the total interaction energy of the VRD ligand being higher than that of the AIN ligand, which is well-correlated with the experimental binding affinity. Furthermore, we have identified the role played by the amino acids LYS0069, LYS0049, LEU0005, ILE0009, CYS0029, GLY0030, HIS0048, PRO0018, ALA0019, CYS0045, TYR0052, TYR0022, PRO0125*, and PHE0126* (LYS0069, LYS0049, GLY0032, LEU0002, and LEU0005) in the VRD↔Lys49-PLA2 (AIN↔Lys49-PLA2) complex. Our simulations are a valuable tool to support the big challenge for neutralizing the damages in victims of snakebites.

New ethionamide boosters and EthR2: structural and energetic analysis.

Ethionamide (ETH) is a high-profile drug for the treatment of patients with multidrug-resistant Mycobacterium tuberculosis and, in order to produce its inhibitory effects, it needs to be bioactivated by monooxygenase EthA. This process is under the control of the transcriptional repressors EthR and EthR2, so that their inhibition results in the boosting of ethionamide activation. Herein, through crystallographic data and computer simulations, we calculated the interaction binding energies of four inhibitors with improved in vitro potency, namely BDM76060 (PDB ID: 6HS1), BDM72201 (PDB ID: 6HRX), BDM76150 (PDB ID: 6HS2) and BDM72719 (PDB ID: 6HRY), in complexes with the transcriptional repressor EthR2, using density functional theory (DFT) within the molecular fractionation with conjugated caps (MFCC) approach. It was observed that these ligands share the same binding site within a 10.0 Å radius of the EthR2 protein; however, their structural particularities have a significant impact on the global energies of systems. The BDM72201 and BDM72719 components are weakly attached to the binding site, while BDM76060 and BDM76150 components produce stronger bonds, corroborating with experimental studies demonstrating that BDM76060 and BDM76150 are more successful in producing inhibitory effects. BDM76060 and BDM76150 have many functional groups that increase the contact surface with the protein and attract a more significant number of amino acid residues, being able to produce polarities that generate stronger interactions. In the current scenario of a growing number of cases of bacterial resistance, the obtained data can be used to guide clinical trials of these inhibitors and other inhibitors that act on the alternative EthR2 pathway, focusing on improving the activity of ethionamide, its effectiveness, a reduction in the treatment time and exposure to cytotoxic effects.

Exploring human porphobilinogen synthase metalloprotein by quantum biochemistry and evolutionary methods.

Previous studies have shown the porphobilinogen synthase (PBGS) zinc-binding mechanism and its conservation among the living cells. However, the precise molecular interaction of zinc with the active center of the enzyme is unknown. In particular, quantum chemistry techniques within the density functional theory (DFT) framework have been the key methodology to describe metalloproteins, when one is looking for a compromise between accuracy and computational feasibility. Considering this, we used DFT-based models within the molecular fractionation with conjugate caps scheme to evaluate the binding energy features of zinc interacting with the human PBGS. Besides, phylogenetic and clustering analyses were successfully employed in extracting useful information from protein sequences to identify groups of conserved residues that build the ions-binding site. Our results also report a conservative assessment of the relevant amino acids, as well as the benchmark analysis of the calculation models used. The most relevant intermolecular interactions in Zn2+-PBGS are due to the amino acids CYS0122, CYS0124, CYS0132, ASP0169, SER0168, ARG0221, HIS0131, ASP0120, GLY0133, VAL0121, ARG0209, and ARG0174. Among these residues, we highlighted ASP0120, GLY0133, HIS0131, SER0168, and ARG0209 by co-occurring in all clusters generated by unsupervised clustering analysis. On the other hand, the triple cysteines at 2.5 Å from zinc (CYS0122, CYS0124, and CYS0132) have the highest energy attraction and are absent in the taxa Viridiplantae, Sar, Rhodophyta, and some Bacteria. Additionally, the performance of the DFT-based models shows that the processing time-dependence is more associated with the choice of the basis set than the exchange-correlation functional.

Fighting COVID-19 / Combatendo a COVID-19

Abstract The current COVID-19 pandemic caused by the novel coronavirus (SARS-CoV2) poses a threat to global health owing to its high rate of spread and severe forms of respiratory infection. The lack of vaccines and antivirals prevents clinical strategies against the disease, creating an emerging need for the development of safe and effective treatments. Strategies for vaccine development include complete vaccines against viruses, subunits, and nucleic acids, but are still in their early stages. Studies carried out to date on possible SARS-CoV2 drug targets highlight glycoprotein S, Mpro (main protease or protease type 3C), and a member of the transmembrane serine protease II families (TMPRSS2). However, due to the pandemic state, priority is given to marketed drugs. These include chloroquine (CQ), hydroxychloroquine (HCQ), nitazoxanide, remdesivir, Lopinavir/ritonavir (LPV / r), in addition to treatment with convalescent plasma. But, therapeutic specific effects against SARS-CoV2 have not yet been verified. Most of the information obtained about treatment is based on preliminary and limited studies. We conclude that, at this time of emergency, the search for new therapies is more urgent due to the need to save lives. Thus, we point out as interesting targets for future more specific research: glycoprotein S, Mpro, and TMPRSS2.

Resumo A pandemia de COVID-19 causada pelo novo Coronavírus (SARS-CoV2) representa uma ameaça à saúde global devido à alta taxa de disseminação e formas graves de infecção respiratória. A falta de vacinas e antivirais específicos dificultam as estratégias clínicas de controle da doença, criando a necessidade urgente do desenvolvimento de tratamentos seguros e eficazes. Com relação as estratégias para o desenvolvimento de vacinas, incluem-se: aquelas com o vírus completo, subunidades e ácidos nucléicos, mas estas ainda estão em estágios iniciais. Já sobre os estudos realizados até o momento buscando novos alvos terapêuticos contra o SARS-CoV2, destacam a glicoproteína S; Mpro (principal protease ou protease tipo 3C) e um membro da família transmembrana serina protease II (TMPRSS2). No entanto, devido ao estado pandêmico, tem sido dada prioridade aos medicamentos comercializados. Estes incluem a cloroquina (CQ); hidroxicloroquina (HCQ); nitazoxanida; remdesivir; Lopinavir / ritonavir (LPV/r); além do tratamento com plasma de pacientes curados. Porém, ainda não há uma estratégia terapêutica contra o SARS-CoV2 totalmente eficaz, e a maioria das informações obtidas sobre o tratamento é baseada em estudos preliminares e limitados. Concluímos então que, neste momento de emergência, a busca por novas terapias é algo urgente devido à necessidade de salvar vidas. Assim finalizamos sugerindo como alvos interessantes para futuras pesquisas específicas: a glicoproteína S, Mpro e o TMPRSS2.

Fighting COVID-19.

The current COVID-19 pandemic caused by the novel coronavirus (SARS-CoV2) poses a threat to global health owing to its high rate of spread and severe forms of respiratory infection. The lack of vaccines and antivirals prevents clinical strategies against the disease, creating an emerging need for the development of safe and effective treatments. Strategies for vaccine development include complete vaccines against viruses, subunits, and nucleic acids, but are still in their early stages. Studies carried out to date on possible SARS-CoV2 drug targets highlight glycoprotein S, Mpro (main protease or protease type 3C), and a member of the transmembrane serine protease II families (TMPRSS2). However, due to the pandemic state, priority is given to marketed drugs. These include chloroquine (CQ), hydroxychloroquine (HCQ), nitazoxanide, remdesivir, Lopinavir/ritonavir (LPV / r), in addition to treatment with convalescent plasma. But, therapeutic specific effects against SARS-CoV2 have not yet been verified. Most of the information obtained about treatment is based on preliminary and limited studies. We conclude that, at this time of emergency, the search for new therapies is more urgent due to the need to save lives. Thus, we point out as interesting targets for future more specific research: glycoprotein S, Mpro, and TMPRSS2.

Clinicopathological analysis of head and neck rhabdomyosarcoma: A series of 10 cases and literature review.

BACKGROUND: To describe the clinicopathological characteristics of a series of head and neck rhabdomyosarcoma (RMS) and to review the literature. MATERIAL AND METHODS: Cases diagnosed as RMS affecting the head and neck region were retrospectively retrieved from the files of two Brazilian institutions from January 2006 to January 2017. Data on clinical features (sex, age and affected site), microscopic subtype, immunohistochemical results, treatment employed and follow-up status were obtained from the patient's medical charts. RESULTS: During the period considered, 10 cases of RMS were identified. Females predominated (4M:6F), the mean age at diagnosis was 16.5 years-old and the orbit was the most affected site (4 cases). Microscopically, most cases were classified as embryonal RMS (6 cases) and the Desmin/Myogenin/Myo-D1 immunohistochemical positivity was useful to confirm the diagnosis. Chemotherapy and radiotherapy were applied to 9 and 8 patients respectively, whereas 2 patients were treated by surgery. Recurrences occurred in 3 patients and distant metastasis in 2 cases. Nine patients were alive in their last follow-up, 3 of them with disease, whereas 1 patient died due to the disease. CONCLUSION: Head and neck RMS is an aggressive malignant neoplasm which demands especial concern to achieve early diagnosis and successful treatment.

Molecular modelling and quantum biochemistry computations of a naturally occurring bioremediation enzyme: Alkane hydroxylase from Pseudomonas putida P1.

Many species of bacteria involved in degradation of n-alkanes have an important constitutional metabolic enzyme, the alkane hydroxylase called AlkB, specialized in the conversion of hydrocarbons molecules that can be used as carbon and/or energy source. This enzyme plays an important role in the microbial degradation of oil, chlorinated hydrocarbons, fuel additives, and many other compounds. A number of these enzymes has been biochemically characterized in detail because the potential of alkane hydroxylases to catalyse high added-value reactions is widely recognized. Nevertheless, the industrial and process bioremediation application of them is restricted, owing to their complex biochemistry, challenging process requirements, and the limited number of their three-dimensional structures. Furthermore, AlkB has great potential as biocatalysts for selective transformation of a wide range of chemically inert unreactive alkanes into reactive chemical precursors that can be used as tools for bioremediation and bioprocesses. Aiming to understand the possible ways the AlkB enzyme Pseudomonas putida P1 interacts with octane, octanol and 1-octyne, we consider its suitable biochemical structure taking into account a 3-D homology modelling. Besides, by using a quantum chemistry computational model based on the density functional theory (DFT), we determine possible protein-substrate interaction regions measured by means of its binding energy simulated throughout the Molecular Fractionation with Conjugated Caps (MFCC) approach.

Fighting COVID-19

Abstract The current COVID-19 pandemic caused by the novel coronavirus (SARS-CoV2) poses a threat to global health owing to its high rate of spread and severe forms of respiratory infection. The lack of vaccines and antivirals prevents clinical strategies against the disease, creating an emerging need for the development of safe and effective treatments. Strategies for vaccine development include complete vaccines against viruses, subunits, and nucleic acids, but are still in their early stages. Studies carried out to date on possible SARS-CoV2 drug targets highlight glycoprotein S, Mpro (main protease or protease type 3C), and a member of the transmembrane serine protease II families (TMPRSS2). However, due to the pandemic state, priority is given to marketed drugs. These include chloroquine (CQ), hydroxychloroquine (HCQ), nitazoxanide, remdesivir, Lopinavir/ritonavir (LPV / r), in addition to treatment with convalescent plasma. But, therapeutic specific effects against SARS-CoV2 have not yet been verified. Most of the information obtained about treatment is based on preliminary and limited studies. We conclude that, at this time of emergency, the search for new therapies is more urgent due to the need to save lives. Thus, we point out as interesting targets for future more specific research: glycoprotein S, Mpro, and TMPRSS2.

Resumo A pandemia de COVID-19 causada pelo novo Coronavírus (SARS-CoV2) representa uma ameaça à saúde global devido à alta taxa de disseminação e formas graves de infecção respiratória. A falta de vacinas e antivirais específicos dificultam as estratégias clínicas de controle da doença, criando a necessidade urgente do desenvolvimento de tratamentos seguros e eficazes. Com relação as estratégias para o desenvolvimento de vacinas, incluem-se: aquelas com o vírus completo, subunidades e ácidos nucléicos, mas estas ainda estão em estágios iniciais. Já sobre os estudos realizados até o momento buscando novos alvos terapêuticos contra o SARS-CoV2, destacam a glicoproteína S; Mpro (principal protease ou protease tipo 3C) e um membro da família transmembrana serina protease II (TMPRSS2). No entanto, devido ao estado pandêmico, tem sido dada prioridade aos medicamentos comercializados. Estes incluem a cloroquina (CQ); hidroxicloroquina (HCQ); nitazoxanida; remdesivir; Lopinavir / ritonavir (LPV/r); além do tratamento com plasma de pacientes curados. Porém, ainda não há uma estratégia terapêutica contra o SARS-CoV2 totalmente eficaz, e a maioria das informações obtidas sobre o tratamento é baseada em estudos preliminares e limitados. Concluímos então que, neste momento de emergência, a busca por novas terapias é algo urgente devido à necessidade de salvar vidas. Assim finalizamos sugerindo como alvos interessantes para futuras pesquisas específicas: a glicoproteína S, Mpro e o TMPRSS2.

Valor nutritivo do feno de capim-jaraguá (Hyparrhenia rufa), em avançado estádio de maturaçäo, tratado com hidróxido de sódio ou amônia anidra. I.Consumo e digestibilidade das fraçöes näo fibrosas e ingestäo de água, em caprinos / Nutritive value of mature Jaraguá grass hay treated with sodium hydroxide or ammonia. I.Intake and digestibility of non-fiber nutrients and water consumption by goats

Dezenove caprinos machos foram utilizados para se avaliar o consumo voluntário e a digestibilidade da fraçäo näo fibrosa de feno de capim-jaraguá (Hyparrhenia rufa) submetido a diferentes tratamentos alcalinos. No grupo-controle (GC), sete animais receberam feno näo tratado, no grupo-soda, seis animais receberam feno tratado com 4 por cento de hidróxido de sódio na matéria natural (MN) e no grupo-amônia (GA), seis caprinos receberam feno tratado com 3 por cento de amônia anidra na MN. Os coeficientes de digestibilidade aparente da MS, MO, PB e EB para os grupos GC, GS e GA foram, respectivamente 51,1, 53,3 e 51,0; 56,2, 58,3 e 58,1; 4,5, -3,0 e 49,0 e 53,1, 53,2 e 54,2. Apenas para o coeficiente de digestibilidade da PB houve diferença significativa (P<0,05) entre os grupos. Os consumos voluntários, em g/kg de peso metabólico, da MS, MO e PB, para os grupos GC,GS e GA foram, respectivamente, 31,3, 33,0 e 44,3; 28,4, 29,2 e 39,4; 1,1, 1,1 e 4,7, e os consumos de energia digestível, em kcal/kg PV0,75 sobrescrito, de 70,1, 70,0 e 98,8. O tratamento com amônia proporcionou consumo significativamente maior (P<0,05) das fraçöes digestíveis. Os animais GS apresentaram consumo de água e excreçäo urinária significativamente maiores (P<0,05). Concluiu-se que 3 por cento de amônia anidra melhorou a qualidade nutricional do feno de capim-jaraguá maduro, por aumentar seu consumo, enquanto o tratamento com soda, sem suplementaçäo de nitrogênio, näo modificou o valor do alimento

Valor nutritivo do feno de capim-jaraguá (Hyparrhenia rufa), em avançado estádio de maturaçäo, tratado com hidróxido de sódio ou amônia anidra. II.Digestibilidade e consumo de fibra, em caprinos / Nutritive value of mature Jaraguá grass hay treated with sodium hydroxide on ammonia. II.Digestibility and fiber intake by goats

Dezenove caprinos machos foram utilizados para se avaliar o consumo voluntário e a digestibilidade da fibra de feno do capim-jaraguá (Hyparrhenia rufa) submetido a diferentes tratamentos alcalinos. No grupo-controle (GC), sete animais receberam feno näo tratado, no grupo soda (GS), seis animais receberam feno tratado com 4 por cento de hidróxido de sódio na matéria natural (MN) e no grupo amônia (GA), seis animais receberam feno tratado com 3 por cento de amônia anidra na MN. Os coeficientes de digestibilidade aparente da FDN, FDA, hemicelulose, celulose e lignina para os grupos GC, GA e GS, foram, respectivamente, 60,1 e 59,8 e 61,8; 55,5, 56,4 e 55,5; 63,2, 66,6 e 64,3; 59,9, 61,3 e 64,2; -28,17, 2,06 e 10,74. Näo houve diferença significativa entre os grupos, exceto na digestibilidade da lignina. Os consumos voluntário, em g/kg de peso metabólico da FDN, FDA, hemicelulose e celulose, para os grupos GC, GA e GS, foram, respectivamente, 24,1, 33,5 e 23,8; 14,0, 22,5 e 15,8; 10,2, 11,0 e 8,1; 13,3, 20,7 e 14,7. O tratamento com amônia proporcionou consumos significativamente maiores das fraçöes digestíveis, com exceçäo da hemicelulose. Concluiu-se que 3 por cento de amônia anidra melhorou a qualidade nutricional do feno de capim-jaraguá maduro, por aumentar seu consumo, enquanto o tratamento com soda, sem suplementaçäo de nitrogênio, näo modificou o valor do alimento