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Pyrazinamide is known to be the most effective treatment against tuberculosis disease and is known to have bacteriostatic action. By targeting the bacterial spores, this drug reduces the chances for the progression of the infection in organisms. In recent years, increased instances of the drug resistance of bacterial strains are reported. Pyrazinamidase, activator for pyrazinamide, leads to resistance against the drug due to mutagenicity across the world. The present study aimed at the quantum mechanistic analysis of mutations in pyrazinamidase to gain insights into the mechanism of this enzyme. Quantum mechanical calculations were performed to analyse the effect of mutations at the metal coordination site using ORCA software program. Moreover, conformational changes in PZase binding cavity has also been analysed due to mutations of binding pocket residues using CASTp server. In order to elucidate the behaviour of the mutant pyrazinamidase, docking of PZA in the binding pocket of PZase was performed using AutoDock Vina. Analysis of results revealed that iron showed weak binding with the metal coordination site of the mutant proteins due to alteration in electron transfer mechanism. The binding cavity of the mutant PZase has undergone major conformational changes as the volume of pocket increased due to bulky R-chains of mutated amino acids. These conformational changes lead to weak binding of the drug at binding cavity of PZase and reduce the drug activation mechanism leading to increased drug resistance in the bacterial strains. [ABSTRACT FROM AUTHOR]

Background: γ-glucosidase (EC 3.2.1.21) catalyzing the γ-glycosidic linkages in polysaccharides is a ubiquitous enzyme with great importance in biofuel and other industries. Enzyme inhibition by glucose has been considered as the major hurdle in the practical applications of this enzyme. Therefore, there has been a continuous search for novel γ-glucosidase with high glucose tolerance and stability at industrial temperature. In the present study, recombinant of γ-glucosidase from Thermococcus radiotolerans has been produced and characterized. Results: The enzyme was overexpressed in Escherichia coli strain BL21 (DE3) codon plus RIPL and purified by selective heat denaturation, ethanol precipitation and anion exchange chromatography. Purified enzyme displayed a band on SDS-PAGE with a molecular weight of 50 kDa. Optimum enzyme activity was found at pH 5, and 85°C, it retained more than 46% activity when incubated at 100°C for 5 min and exhibited 80% activity in the presence of 800 mM glucose. Km and Vmax values of the purified enzyme were found as 16.3 mM of pNPG and 25.8 μ moles per min. Molecular docking studies have shown a strong binding affinity of pNPG with the enzyme active site consisting of Glu365, Asn266, and Trp295 as major the active site amino acids. MD simulation analysis has shown a significantly high stability of enzyme active site and high potential of enzyme substrate complex formation. [ABSTRACT FROM AUTHOR]

• Synthesis of benzofuran derivatives. • In vitro acetylcholinesterase and butyrylcholinesterase inhibitory activity. • Identification of a novel class of anti-alzheimer agents. • Molecular docking studies. We have synthesized novel benzofuran derivatives (1–20), characterized through different spectroscopic techniques such as 1HNMR, 13CNMR, HREI-MS and screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. All derivatives showed inhibitory activities having IC 50 values ranging from 0.70 ± 0.01 to 28.10 ± 0.50 µ M (against AChE), while 0.80 ± 0.01 to 31.20 ± 0.60 µ M (against BuChE) as compared to the standard drug Donepezil (IC 50 = 2.16 ± 0.12 and 4.50 ± 0.10 µ M, respectively). Except derivative 5, all other derivatives of the series showed good inhibitory activity against both acetylcholinesterase and butyrylcholinesterase, but some analogues like 2, 4, 7, 14, 15, and 16 displayed many folds better inhibitory activity than the standard drug donepezil. The influences of substituents on inhibitory activity were superficially resonated via the structure-activity relationship. We established molecular docking and MD simulation studies to confirm the binding interaction between potent derivatives and active sites of enzymes. [Display omitted] [ABSTRACT FROM AUTHOR]