The study involves the isolation and characterization of a serine peptidase, named SP, from Pseudomonas
aeruginosa. In addition to basic characterization, the protein was engineered, by site-directed mutagenesis of selected
non-catalytic residues, to increase its thermal stability and catalytic activity. Among the eight-point mutations,
predicted by FireProt, two mutants, A29G and V336I, yielded a positive impact. The Tm of A29G and V336I
showed an increase by 5 °C and also a substantial increase in residual activity of the enzyme at elevated temperature.
Moreover, the catalytic activity of A29G and V336I also showed an increase of 1.4-fold activity, compared to
the wild-type (WT). Moreover, molecular docking simulations also predicted better substrate affinity of themutants.
Wehave also performed molecular dynamics (MD) simulations at 315 and 345 K, and theMDdata at 345 K
demonstrates improved thermostability for the mutants, compared to theWT. Our findings not only contribute
to a better understanding of the structure-stability-activity relationship of SP but also highlights, that modification
of non-catalytic residues could also promote favourable catalytic behaviour.

Dengue symptoms include alteration of blood coagulation and fibrinolysis, causing severe hemorrhage
and death. Here, we demonstrate that higher concentration of plasmin, the human fibrinolytic
factor, in blood meal enhances dengue virus (DENV) infection in mosquitomidgut and dissemination in
mosquitoes. We also show that mosquitoes express a plasmin-selective Kazal-type inhibitor (AaTI) in
the midgut to inhibit plasmin proteolysis and revert the enhanced infection. Using bio-layer interferometry,
we show that DENV, plasmin, and AaTI interact to form a tripartite complex. Eventually,
plasmin increases midgut internalization of dextran molecules and this is reverted by AaTI. Our study
demonstrates that (1) DENV recruits plasmin to increase local proteolytic activity in the midgut, thus
degrading the glycocalyx and enhancing DENV internalization and (2) AaTI can act as a transmissionblocking
agent by inhibiting plasmin proteolysis. Our results indicate that dengue pathogenesis
enhances DENV fitness by increasing its infectivity to mosquitoes.

Redox signaling and homeostasis are essential for cell survival and the immune response. Peroxiredoxin (Prx) modulates the level of H2O2 as a redox signal through H2O2 decomposition. The redox activity of thioredoxin (Trx) is required as a reducing equivalent to regenerate Prx. Edwardsiella piscicida is an opportunistic Gram-negative enteric pathogen that secretes a novel Trx-like effector protein, ETAE_2186 (Trxlp). Trxlp has unique structural properties compared with other Trx proteins. In enzymatic and binding assays, we confirmed Trxlp to be redox-inactive due to the low reactivity and flexibility of the resolving cysteine residue, C35, at the active site motif “31WCXXC35”. We identified key residues near the active site that are critical for reactivity and flexibility of C35 by site-directed mutagenesis analysis. NMR titration experiment demonstrated prolong inhibitory interaction of Trxlp with Prx1 resulting in the …

The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.

The prevalence of various hepatic diseases increases dramatically worldwide and regarded as a serious health problem. Sirtuins are one of the main strategic controllers of different cellular processes, including cell cycle, mitochondrial biogenesis, insulin secretion, redox balance, inflammation, and apoptosis. SIRT1 is the most prominent and broadly studied member of sirtuins that implicated in health status and longevity. Therefore, targeting the SIRT1 signaling pathways may be a reasonable therapeutic approach to treat different diseases, including hepatic disorders. Flavonoids are polyphenolic compounds widely present in different plants and possess beneficial effects against diverse diseases. In this review, we focused on the flavonoids, (−)-epicatechin, ampelopsin, baicalin, delphinidin, fisetin, epigallocatechin-3-gallate, luteolin, pinocembrin, quercetin, silibinin, trans-chalcone and xanthohumol, to verify …

The prevalence of various hepatic diseases increases dramatically worldwide and regarded as a serious health problem. Sirtuins are one of the main strategic controllers of different cellular processes, including cell cycle, mitochondrial biogenesis, insulin secretion, redox balance, inflammation, and apoptosis. SIRT1 is the most prominent and broadly studied member of sirtuins that implicated in health status and longevity. Therefore, targeting the SIRT1 signaling pathways may be a reasonable therapeutic approach to treat different diseases, including hepatic disorders. Flavonoids are polyphenolic compounds widely present in different plants and possess beneficial effects against diverse diseases. In this review, we focused on the flavonoids, (−)-epicatechin, ampelopsin, baicalin, delphinidin, fisetin, epigallocatechin-3-gallate, luteolin, pinocembrin, quercetin, silibinin, trans-chalcone and xanthohumol, to verify …

Introduction: Cyclophosphamide (CP) causes redox imbalance and its use is associated with marked cardiotoxicity that limits its clinical applications. The present study investigated the protective effects of acetovanillone (AV) and edaravone (ED) against CP-induced oxidative stress and cardiac damage, emphasizing the role of PI3K/Akt/mTOR and Nrf2 signaling.
Materials and Methods: Rats received either AV (100 mg/kg) or ED (20 mg/kg) orally for 10 days and CP (200 mg/kg) on day 7. At day 11, the rats were sacrificed, and samples were collected for analysis.
Results: AV and ED ameliorated serum troponin I, CK-MB, LDH, AST and ALP, and prevented cardiac histological alterations in CP-intoxicated rats. Both treatments decreased cardiac lipid peroxidation and enhanced GSH, SOD and cytoglobin in CP-induced rats. AV and ED downregulated Keap1, whereas increased the expression of PI3K, Akt, mTOR and Nrf2 in the heart of rats received CP. Additionally, the binding modes of AV and ED to Keap1 were pinpointed in silico using molecular docking simulations.
Conclusion: AV and ED prevent CP cardiotoxicity by attenuating oxidative stress and tissue injury, and modulating cytoglobin, and PI3K/Akt/mTOR and Keap1/Nrf2 signaling. Therefore, AV and ED may represent promising agents that can prevent cardiac injury in patients receiving CP.

Introduction: Cyclophosphamide (CP) causes redox imbalance and its use is associated with marked cardiotoxicity that limits its clinical applications. The present study investigated the protective effects of acetovanillone (AV) and edaravone (ED) against CP-induced oxidative stress and cardiac damage, emphasizing the role of PI3K/Akt/mTOR and Nrf2 signaling.
Materials and Methods: Rats received either AV (100 mg/kg) or ED (20 mg/kg) orally for 10 days and CP (200 mg/kg) on day 7. At day 11, the rats were sacrificed, and samples were collected for analysis.
Results: AV and ED ameliorated serum troponin I, CK-MB, LDH, AST and ALP, and prevented cardiac histological alterations in CP-intoxicated rats. Both treatments decreased cardiac lipid peroxidation and enhanced GSH, SOD and cytoglobin in CP-induced rats. AV and ED downregulated Keap1, whereas increased the expression of PI3K, Akt, mTOR and Nrf2 in the heart of rats received CP. Additionally, the binding modes of AV and ED to Keap1 were pinpointed in silico using molecular docking simulations.
Conclusion: AV and ED prevent CP cardiotoxicity by attenuating oxidative stress and tissue injury, and modulating cytoglobin, and PI3K/Akt/mTOR and Keap1/Nrf2 signaling. Therefore, AV and ED may represent promising agents that can prevent cardiac injury in patients receiving CP.

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