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BACKGROUND: The endoplasmic reticulum (ER) is the central hub for protein quality control, where the protein disulfide isomerases (PDIs), encoded by at least 21 genes, play a pivotal role. These multifunctional proteins contribute to disulfide bond formation, proper folding, and protein modifications, and may act as hormone-binding proteins (e.g., steroids), influencing hormone biology. The interplay between ER proteostasis, PDIs, and epididymis-a crucial site for sperm maturation-remains largely understudied. OBJECTIVES: This study characterizes transcriptional signatures of Pdi genes in the epididymis. MATERIAL AND METHODS: Transcriptional profiles of selected Pdi genes were assessed in adult Wistar rat tissues, and epididymis under different experimental conditions (developmental stages, surgical castration, and efferent ductules ligation [EDL]). In silico bioinformatic analyses identified expression trends of this gene family in human epididymal segments. RESULTS: P4hb, Pdia3, Pdia5, Pdia6, Erp44, Erp29, and Casq1 transcripts were detected in both reproductive and non-reproductive tissues, while Casq2 exhibited higher abundance in vas deferens, prostate, and heart. Pdilt, highly expressed in testis, and Pdia2, highly expressed in heart, showed minimal mRNA levels in the epididymis. In the mesonephric duct, epididymal embryonic precursor, P4hb, Pdia3, Pdia5, Pdia6, and Erp29 mRNAs were found at gestational day (GD) 17.5. Except for Erp29, which remained stable, these Pdi transcript levels increased from GD17.5 to GD20.5, when epididymal morphogenesis occurs, and were maintained to varying degrees in the epididymis during postnatal development. Surgical castration downregulated P4hb, Pdia3, Pdia5, Pdia6, Pdilt and Erp29 transcripts, an effect reversed by testosterone replacement. Conversely, transcript levels remained unaffected by EDL, except P4hb, which was reduced in caput epididymis. All 21 PDI genes exhibited diverse transcriptional profiles across the human epididymis. DISCUSSION AND CONCLUSION: The findings lay the foundations to explore Pdi genes in epididymal biology. As a considerable proportion of male infertility cases are idiopathic, targeting hormonal regulation of protein quality control in epididymis represents a route to address male infertility and advance therapeutic interventions in this domain.

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This work proposes for the first time protecting-reflecting on both sides of plated mirrors and a solution to polycarbonate surface vulnerability to weathering and scratching using tungsten disulfide (WS2) by mechanical polishing. The ability of the dynamic chemical plating (DCP) technique to deposit Ag films at the nanometer scale on a polycarbonate (PC) substrate and its characteristics to be metallized is also shown. These deposits hold significant promise for concentrated solar power (CSP) applications. Complementarily, the application of WS2 as a reflective film for CSP by mechanical polishing on smooth polycarbonate surfaces is both novel and practical. This technique is innovative and scalable without needing reactants or electrical potential, making it highly applicable in real-world scenarios, including, potentially, on-site maintenance. The effects of surface morphology and adhesion, and the reflectivity parameters of the silver metallic surfaces were investigated. Wettability was investigated because it is important for polymeric surfaces in the activation and metal deposition immediately after redox reactions. The flame technique improved wettability by modifying the surface with carbonyl and carboxyl functional groups, with PC among the few industrial polymers that resisted such a part of the process. The change in the chemical composition, roughness, and wettability of the surfaces effectively improved the adhesion between the Ag film and the PC substrate. However, it did not significantly affect the adhesion between PC and WS2 and showed its possible implementation as a first surface mirror. Overall, this work provides a scalable, innovative method for improving the durability and reflectivity of polycarbonate-based mirrors, with significant implications for CSP applications.

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This paper presents an application for a molybdenum disulfide nanomaterial with multiwalled carbon nanotubes (MoS2@MWCNT/E) in a modified electrode substrate for the detection of uric acid (UA). The modified electrode generates a substantial three-fold increase in the anodic peak current for UA compared to the unmodified MWCNT electrode (MWCNT/E). The MoS2@MWCNT/E surface was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and electrochemical impedance spectroscopy (EIS). The achieved detection limit stood at 0.04 µmol/L, with a relative standard deviation (RSD) of 2.0% (n = 10). The method's accuracy, assessed through relative error and percent recovery, was validated using a urine standard solution spiked with known quantities of UA.

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Redox processes can modulate vascular pathophysiology. The endoplasmic reticulum redox chaperone protein disulfide isomerase A1 (PDIA1) is overexpressed during vascular proliferative diseases, regulating thrombus formation, endoplasmic reticulum stress adaptation, and structural remodeling. However, both protective and deleterious vascular effects have been reported for PDIA1, depending on the cell type and underlying vascular condition. Further understanding of this question is hampered by the poorly studied mechanisms underlying PDIA1 expression regulation. Here, we showed that PDIA1 mRNA and protein levels were upregulated (average 5-fold) in the intima and media/adventitia following partial carotid ligation (PCL). Our search identified that miR-204-5p and miR-211-5p (miR-204/211), two broadly conserved miRNAs, share PDIA1 as a potential target. MiR-204/211 was downregulated in vascular layers following PCL. In isolated endothelial cells, gain-of-function experiments of miR-204 with miR mimic decreased PDIA1 mRNA while having negligible effects on markers of endothelial activation/stress response. Similar effects were observed in vascular smooth muscle cells (VSMCs). Furthermore, PDIA1 downregulation by miR-204 decreased levels of the VSMC contractile differentiation markers. In addition, PDIA1 overexpression prevented VSMC dedifferentiation by miR-204. Collectively, we report a new mechanism for PDIA1 regulation through miR-204 and identify its relevance in a model of vascular disease playing a role in VSMC differentiation. This mechanism may be regulated in distinct stages of atherosclerosis and provide a potential therapeutic target.

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The interplay between metal ion binding and the activity of thiol proteins, particularly within the protein disulfide isomerase family, remains an area of active investigation due to the critical role that these proteins play in many vital processes. This research investigates the interaction between recombinant human PDIA1 and zinc ions, focusing on the subsequent implications for PDIA1's conformational stability and enzymatic activity. Employing isothermal titration calorimetry and differential scanning calorimetry, we systematically compared the zinc binding capabilities of both oxidized and reduced forms of PDIA1 and assessed the structural consequences of this interaction. Our results demonstrate that PDIA1 can bind zinc both in reduced and oxidized states, but with significantly different stoichiometry and more pronounced conformational effects in the reduced form of PDIA1. Furthermore, zinc binding was observed to inhibit the catalytic activity of reduced-PDIA1, likely due to induced alterations in its conformation. These findings unveil a potential regulatory mechanism in PDIA1, wherein metal ion binding under reductive conditions modulates its activity. Our study highlights the potential role of zinc in regulating the catalytic function of PDIA1 through conformational modulation, suggesting a nuanced interplay between metal binding and protein stability in the broader context of cellular redox regulation.

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SUMMARY OBJECTIVE: We aimed to examine the effect of remission status on thiol-disulfide homeostasis in celiac patients and thus to indirectly determine the effect of oxidative stress and inflammation caused by non-compliance with the diet. METHODS: Between February 2019 and December 2021, 117 patients diagnosed with celiac disease were included in this prospective randomized and controlled study. In addition to routine tests of celiac patients, thiol and disulfide measurements were made from the blood both at the beginning of the study and at the end of the first year. RESULTS: While 52 of the patients (44.4%) were in remission, 65 patients (55.6%) were not. There was an evident increase in native thiol levels of the patients who were initially not in remission but went into at the end of the first year (347.4±46.7 μmol/L vs. 365.3±44.0 μmol/L; p=0.001). Mean plasma disulfide levels of patients with celiac going into remission became reduced in the first year from the level of 14.5±5.1 μmol/L down to 8.9±4.2 μmol/L (p<0.001). In celiac patients who entered remission, disulfide and anti-tissue transglutaminase immunoglobulin A levels decreased in a correlation (r=0.526; p<0.001). CONCLUSION: Not being in remission in celiac disease leads to increased oxidative stress, and thiol-disulfide homeostasis is an indirect indicator of this. Additionally, providing remission in celiac patients reduces oxidative stress.

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The adsorption of CO, NO, and O2 molecules onto Cu, Ag, and Au atoms placed in the S vacancies of a WS2 monolayer was elucidated within dispersion-corrected density functional theory. The binding energies computed for embedded defects into S vacancies were 2.99 (AuS), 2.44 (AgS), 3.32 eV (CuS), 3.23 (Au2S2), 2.55 (Ag2S2), and 3.48 eV/atom (Cu2S2), respectively. The calculated diffusion energy barriers from an S vacancy to a nearby site for Cu, Ag, and Au were 2.29, 2.18, and 2.16 eV, respectively. Thus, the substitutional atoms remained firmly fixed at temperatures above 700 K. Similarly, the adsorption energies showed that nitric oxide and carbon oxide molecules exhibited stronger chemisorption than O2 molecules on any of the metal atoms (Au, Cu, or Ag) placed in the S vacancies of the WS2 monolayer. Therefore, the adsorption of O2 did not compete with NO or CO adsorption and did not displace them. The density of states showed that a WS2 monolayer modified with a Cu, Au, or Ag atom could be used to design sensing devices, based on electronic or magnetic properties, for atmospheric pollutants. More interestingly, the adsorption of CO changed only the electronic properties of the MoS2-AuS monolayer, which could be used for sensing applications. In contrast, the O2 molecule was chemisorbed more strongly than CO or NO on Au2S2, Cu2S2, or Ag2S2 placed into di-S vacancies. Thus, if the experimental system is exposed to air, the low quantities of O2 molecules present should result in the oxidation of the metallic atoms. Furthermore, the O2 molecules adsorbed on WS2-Au2S2 and WS2-CuS introduced a half-metallic behavior, making the system suitable for applications in spintronics.

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BACKGROUND AND AIMS: Redox signaling is involved in the pathophysiology of aortic aneurysm/dissection. Protein Disulfide Isomerases and its prototype PDIA1 are thiol redox chaperones mainly from endoplasmic reticulum (ER), while PDIA1 cell surface pool redox-regulates thrombosis, cytoskeleton remodeling and integrin activation, which are mechanisms involved in aortic disease. Here we investigate the roles of PDIA1 in aortic dissection. METHODS: Initially, we assessed the outcome of aortic aneurysm/dissection in transgenic PDIA1-overexpressing FVB mice using a model of 28-day exposure to lysyl oxidase inhibitor BAPN plus angiotensin-II infusion. In a second protocol, we assessed the effects of PDIA1 inhibitor isoquercetin (IQ) against aortic dissection in C57BL/6 mice exposed to BAPN for 28 days. RESULTS: Transgenic PDIA1 overexpression associated with ca. 50% (p = 0.022) decrease (vs.wild-type) in mortality due to abdominal aortic rupture and protected against elastic fiber breaks in thoracic aorta. Conversely, exposure of mice to IQ increased thoracic aorta dissection-related mortality rates, from ca. 18%-50% within 28-days (p = 0.019); elastic fiber disruption and collagen deposition were also enhanced. The structurally-related compound diosmetin, which does not inhibit PDI, had negligible effects. In parallel, stretch-tension curves indicated that IQ amplified a ductile-type of biomechanical failure vs. control or BAPN-exposed mice aortas. IQ-induced effects seemed unassociated with nonspecific antioxidant effects or ER stress. In both models, echocardiographic analysis of surviving mice suggested that aortic rupture was dissociated from progressive dilatation. CONCLUSIONS: Our data indicate a protective role of PDIA1 against aortic dissection/rupture and potentially uncovers a novel integrative mechanism coupling redox and biomechanical homeostasis in vascular remodeling.

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Peptides are remarkably interesting alternatives to several applications. In particular, antimicrobial sequences have raised major interest of the scientific community due to the resistance acquired by commonly used antibiotics. Amongst these, some dimeric peptides have shown very promising characteristics as strong biological activities and resistance against degradation by peptidases. However, despite such promising characteristics, a relatively small number of studies address dimeric peptides, mainly due to the synthesis-related obstacles in their production, whereas the well-implemented routines of solid phase peptide synthesis-which includes the possibility of automation-makes life significantly easier. Here, we present kinetic investigations of the dimerization of a cysteine-containing sequence to obtain the homodimeric antimicrobial peptide homotarsinin. Based on the structural and membrane interaction data already available for the dimer and its monomeric chain, we have proposed distinct dimerization protocols in selected environments, namely, aqueous buffer, TFE:H2O and micellar solutions. The experimental results were adjusted by a theoretical model. Both the kinetic profiles and the reaction yields are dependent on the reaction medium, clearly indicating that aggregation, peptide structure, and peptide-membrane interactions play major roles in the formation of the disulfide bond. Finally, the rationalization of the different aspects addressed here is expected to contribute to research and applications that demand the obtainment of dimeric peptides.

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Gallesia integrifolia, a notable species in the Atlantic Forest, has been traditionally employed in folk medicine for treating rheumatism, asthma, and worms. This study investigated the cellular antioxidant, antiproliferative, and anti-inflammatory activities of the essential oils (EOs) and crude extracts (CEs) from G. integrifolia flowers, fruits, and leaves. The chemical identification of EOs was performed by GC-MS and CEs by UHPLC-MS. Cellular antioxidant and anti-inflammatory activities were assessed through mouse macrophage cell culture. In addition, the antiproliferative potential was evaluated in gastric, colorectal, breast, and lung tumor cell lines and non-tumor VERO cells. EOs predominantly contained organosulfur compounds in flowers (96.29%), fruits (94.94%), and leaves (90.72%). We found the main compound is 2,2'-Disulfanediyldiethanethiol in the EOs of flowers (47.00%), leaves (41.82%), and fruits (44.39%). Phenolic compounds were identified in CEs. The EOs and CEs demonstrated potential against the tumor cell lines tested (GI50 between 51 and 230 µg/mL). The selectivity index values were greater than 1.0 (1.01 to 3.37), suggesting a relative safety profile. Moreover, the anti-inflammatory activity IC50 ranged from 36.00 to 268 µg/mL, and the cellular oxidation inhibition ranged from 69% to 82%. The results suggest that oils and extracts derived from G. integrifolia have potential for use in various industrial sectors.

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Effective control of diseases transmitted by Aedes aegypti is primarily achieved through vector control by chemical insecticides. However, the emergence of insecticide resistance in A. aegypti undermines current control efforts. Arachnid venoms are rich in toxins with activity against dipteran insects and we therefore employed a panel of 41 spider and 9 scorpion venoms to screen for mosquitocidal toxins. Using an assay-guided fractionation approach, we isolated two peptides from the venom of the tarantula Lasiodora klugi with activity against adult A. aegypti. The isolated peptides were named U-TRTX-Lk1a and U-TRTX-Lk2a and comprised 41 and 49 residues with monoisotopic masses of 4687.02 Da and 5718.88 Da, respectively. U-TRTX-Lk1a exhibited an LD50 of 38.3 pmol/g when injected into A. aegypti and its modeled structure conformed to the inhibitor cystine knot motif. U-TRTX-Lk2a has an LD50 of 45.4 pmol/g against adult A. aegypti and its predicted structure conforms to the disulfide-directed ß-hairpin motif. These spider-venom peptides represent potential leads for the development of novel control agents for A. aegypti.

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The interactions of the heme iron of hemeproteins with sulfide and disulfide compounds are of potential interest as physiological signaling processes. While the interaction with hydrogen sulfide has been described computationally and experimentally, the reaction with disulfide, and specifically the molecular mechanism for ligand binding has not been studied in detail. In this work, we study the association process for disulfane and its conjugate base disulfanide at different pH conditions. Additionally, by means of advanced sampling techniques based on multiple steered molecular dynamics, we provide free energy profiles for ligand migration for both acid/base species, showing a similar behavior to the previously reported for the related H2S/HS¯ pair. Finally, we studied the ligand interchange reaction (H2O/H2S, HS¯ and H2O/HSSH, HSS¯) by means of hybrid quantum mechanics-molecular mechanics calculations. We show that the anionic species are able to displace more efficiently the H2O bound to the iron, and that the H-bond network in the distal cavity can help the neutral species to perform the reaction. Altogether, we provide a molecular explanation for the experimental information and show that the global association process depends on a fine balance between the migration towards the active site and the ligand interchange reaction.

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Defective molybdenum disulfide (MoS2) monolayers (MLs) modified with coinage metal atoms (Cu, Ag and Au) embedded in sulfur vacancies are studied at a dispersion-corrected density functional level. Atmospheric constituents (H2, O2 and N2) and air pollutants (CO and NO), known as secondary greenhouse gases, are adsorbed on up to two atoms embedded into sulfur vacancies in MoS2 MLs. The adsorption energies suggest that the NO (1.44 eV) and CO (1.24 eV) are chemisorbed more strongly than O2 (1.07 eV) and N2 (0.66 eV) on the ML with a cooper atom substituting for a sulfur atom. Therefore, the adsorption of N2 and O2 does not compete with NO or CO adsorption. Besides, NO adsorbed on embedded Cu creates a new level in the band gap. In addition, it was found that the CO molecule could directly react with the pre-adsorbed O2 molecule on a Cu atom, forming the complex OOCO, via the Eley-Rideal reaction mechanism. The adsorption energies of CO, NO and O2 on Au2S2, Cu2S2 and Ag2S2 embedded into two sulfur vacancies were competitive. Charge transference occurs from the defective MoS2 ML to the adsorbed molecules, oxidizing the later ones (NO, CO and O2) since they act as acceptors. The total and projected density of states reveal that a MoS2 ML modified with copper, gold and silver dimers could be used to design electronic or magnetic devices for sensing applications in the adsorption of NO, CO and O2 molecules. Moreover, NO and O2 molecules adsorbed on MoS2-Au2s2 and MoS2-Cu2s2 introduce a transition from metallic to half-metallic behavior for applications in spintronics. These modified monolayers are expected to exhibit chemiresistive behavior, meaning their electrical resistance changes in response to the presence of NO molecules. This property makes them suitable for detecting and measuring NO concentrations. Also, modified materials with half-metal behavior could be beneficial for spintronic devices, particularly those that require spin-polarized currents.

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Phα1ß (PnTx3-6) is a neurotoxin from the spider Phoneutria nigriventer venom, originally identified as an antagonist of two ion channels involved in nociception: N-type voltage-gated calcium channel (CaV2.2) and TRPA1. In animal models, Phα1ß administration reduces both acute and chronic pain. Here, we report the efficient bacterial expression system for the recombinant production of Phα1ß and its 15N-labeled analogue. Spatial structure and dynamics of Phα1ß were determined via NMR spectroscopy. The N-terminal domain (Ala1-Ala40) contains the inhibitor cystine knot (ICK or knottin) motif, which is common to spider neurotoxins. The C-terminal α-helix (Asn41-Cys52) stapled to ICK by two disulfides exhibits the µs-ms time-scale fluctuations. The Phα1ß structure with the disulfide bond patterns Cys1-5, Cys2-7, Cys3-12, Cys4-10, Cys6-11, Cys8-9 is the first spider knottin with six disulfide bridges in one ICK domain, and is a good reference to other toxins from the ctenitoxin family. Phα1ß has a large hydrophobic region on its surface and demonstrates a moderate affinity for partially anionic lipid vesicles at low salt conditions. Surprisingly, 10 µM Phα1ß significantly increases the amplitude of diclofenac-evoked currents and does not affect the allyl isothiocyanate (AITC)-evoked currents through the rat TRPA1 channel expressed in Xenopus oocytes. Targeting several unrelated ion channels, membrane binding, and the modulation of TRPA1 channel activity allow for considering Phα1ß as a gating modifier toxin, probably interacting with S1-S4 gating domains from a membrane-bound state.

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Gene delivery has emerged as a promising alternative to conventional treatment approaches, allowing for the manipulation of gene expression through gene insertion, deletion, or alteration. However, the susceptibility of gene delivery components to degradation and challenges associated with cell penetration necessitate the use of delivery vehicles for effective functional gene delivery. Nanostructured vehicles, such as iron oxide nanoparticles (IONs) including magnetite nanoparticles (MNPs), have demonstrated significant potential for gene delivery applications due to their chemical versatility, biocompatibility, and strong magnetization. In this study, we developed an ION-based delivery vehicle capable of releasing linearized nucleic acids (tDNA) under reducing conditions in various cell cultures. As a proof of concept, we immobilized a CRISPR activation (CRISPRa) sequence to overexpress the pink1 gene on MNPs functionalized with polyethylene glycol (PEG), 3-[(2-aminoethyl)dithio]propionic acid (AEDP), and a translocating protein (OmpA). The nucleic sequence (tDNA) was modified to include a terminal thiol group and was conjugated to AEDP's terminal thiol via a disulfide exchange reaction. Leveraging the natural sensitivity of the disulfide bridge, the cargo was released under reducing conditions. Physicochemical characterizations, including thermogravimetric analysis (TGA) and Fourier-transform infrared (FTIR) spectroscopy, confirmed the correct synthesis and functionalization of the MNP-based delivery carriers. The developed nanocarriers exhibited remarkable biocompatibility, as demonstrated by the hemocompatibility, platelet aggregation, and cytocompatibility assays using primary human astrocytes, rodent astrocytes, and human fibroblast cells. Furthermore, the nanocarriers enabled efficient cargo penetration, uptake, and endosomal escape, with minimal nucleofection. A preliminary functionality test using RT-qPCR revealed that the vehicle facilitated the timely release of CRISPRa vectors, resulting in a remarkable 130-fold overexpression of pink1. We demonstrate the potential of the developed ION-based nanocarrier as a versatile and promising gene delivery vehicle with potential applications in gene therapy. The developed nanocarrier is capable of delivering any nucleic sequence (up to 8.2 kb) once it is thiolated using the methodology explained in this study. To our knowledge, this represents the first MNP-based nanocarrier capable of delivering nucleic sequences under specific reducing conditions while preserving functionality.

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The mechanism of the metal centered reduction of metmyoglobin (MbFeIII) by inorganic disulfide species has been studied by combined spectroscopic and kinetic analyses, under argon atmosphere. The process is kinetically characterized by biexponential time traces, for variable ratios of excess disulfide to protein, in the pH interval 6.6-8.0. Using UV-vis and resonance Raman spectroscopies, we observed that MbFeIII is converted into a low spin hexacoordinated ferric complex, tentatively assigned as MbFeIII(HSS-)/MbFeIII(SS2-), in an initial fast step. The complex is slowly converted into a pentacoordinated ferrous form, assigned as MbFeII according to the resonance Raman records. The reduction is a pH-dependent process, but independent of the initial disulfide concentration, suggesting the unimolecular decomposition of the intermediate complex following a reductive homolysis. We estimated the rate of the fast formation of the complex at pH 7.4 (kon = 3.7 × 103 M-1 s-1), and a pKa2 = 7.5 for the equilibrium MbFeIII(HSS-)/MbFeIII(SS2-). Also, we estimated the rate for the slow reduction at the same pH (kred = 10-2 s-1). A reaction mechanism compliant with the experimental results is proposed. This mechanistic study provides a differential kinetic signature for the reactions of disulfide compared to sulfide species on metmyoglobin, which may be considered in other hemeprotein systems.

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This study aimed to investigate how an ultralow content of a molybdenum disulfide (MoS2) two-dimensional particle affects the photodegradation mechanism of polystyrene (PS). Here, an accelerated weathering study was presented on neat polystyrene and its nanocomposites produced with 0.001, 0.002, 0.003 and 0.005 wt% of molybdenum disulfide (MoS2) exposed for various irradiation intervals (up to 8 weeks). The polymer photo-transformations were monitored using size exclusion chromatography (SEC), infrared spectroscopy (FTIR), and UV-Vis spectroscopy. The FTIR and UV/Vis results indicate that the PS degradation mechanism was not altered by the presence of MoS2 particles; however, the degradation reactions were slowed down at higher MoS2 contents (>0.003%). The SEC results proved the stabilizer effect due to MoS2 particles, where M¯n, M¯w, and M¯w/M¯n values after 8 weeks were less modified when compared with the neat PS results. The MoS2 acted as a UV stabilizer, and these two-dimensional particles acted by deactivating the free radicals generated by the PS matrix, even considering the low amount of the filler (<0.005 wt%).

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ß-Lactoglobulin (ß-Lg) is the main protein in whey and is known for its allergenicity and resistance to the digestion of pepsin and trypsin. The UV-C photoinduced cleavage of disulfide bonds in ß-Lactoglobulin, as promoted by excitation of tryptophan residues (Trp), is shown to induce changes in the protein's secondary structure, significantly reducing the protein's resistance to pepsin digestion. The UV-C light-induced changes in the protein secondary structure are marked by an increase in the contribution of ß-sheet and α-helix structures with a concomitantly smaller contribution of the ß-turn structural motif. The photoinduced cleavage of disulfide bonds in ß-Lg has an apparent quantum yield of ф = 0.0015 ± 0.0003 and was shown by transient absorption laser flash photolysis to arise by two different pathways: a) the reduction of the disulfide bond Cys66Cys160 occurs by direct electron transfer from the triplet-excited 3Trp to the disulfide bond due to the existence of a CysCys/Trp triad (Cys66Cys160/Trp61) and b) the reduction of the buried Cys106Cys119 disulfide bond involves a reaction with a solvated electron originated by the photoejection of electrons from the triplet-excited 3Trp decay. The in vitro gastric digestion index for UV-C-treated ß-Lg is revealed to have increased significantly by 36 ± 4 % and 9 ± 2 % under simulated elderly and young adult digestive conditions, respectively. When compared to the native protein, the peptide mass fingerprint profile of digested UV-C-treated ß-Lg shows a higher content and variety of peptides, including the production of some exclusive bioactive peptides such as PMHIRL and EKFDKALKALPMH.

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Among the most studied semiconducting transition metal dichalcogenides (TMDCs), WS2 showed several advantages in comparison to their counterparts, such as a higher quantum yield, which is an important feature for quantum emission and lasing purposes. We studied transferred monolayers of WS2 on a drilled Si3N4 substrate in order to have insights about on how such heterostructure behaves from the Raman and photoluminescence (PL) measurements point of view. Our experimental findings showed that the Si3N4 substrate influences the optical properties of single-layer WS2. Beyond that, seeking to shed light on the causes of the PL quenching observed experimentally, we developed density functional theory (DFT) based calculations to study the thermodynamic stability of the heterojunction through quantum molecular dynamics (QMD) simulations as well as the electronic alignment of the energy levels in both materials. Our analysis showed that along with strain, a charge transfer mechanism plays an important role for the PL decrease.

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Venoms from tarantulas contain low molecular weight vasodilatory compounds whose biological action is conceived as part of the envenomation strategy due to its propagative effects. However, some properties of venom-induced vasodilation do not match those described by such compounds, suggesting that other toxins may cooperate with these ones to produce the observed biological effect. Owing to the distribution and function of voltage-gated ion channels in blood vessels, disulfide-rich peptides isolated from venoms of tarantulas could be conceived into potential vasodilatory compounds. However, only two peptides isolated from spider venoms have been investigated so far. This study describes for the first time a subfraction containing inhibitor cystine knot peptides, PrFr-I, obtained from the venom of the tarantula Poecilotheria regalis. This subfraction induced sustained vasodilation in rat aortic rings independent of vascular endothelium and endothelial ion channels. Furthermore, PrFr-I decreased calcium-induced contraction of rat aortic segments and reduced extracellular calcium influx to chromaffin cells by the blockade of L-type voltage-gated calcium channels. This mechanism was unrelated to the activation of potassium channels from vascular smooth muscle, since vasodilation was not affected in the presence of TEA, and PrFr-I did not modify the conductance of the voltage-gated potassium channel Kv10.1. This work proposes a new envenomating function of peptides from venoms of tarantulas, and establishes a new mechanism for venom-induced vasodilation.