Bothrops snake venom L-amino acid oxidases impair biofilm formation of clinically relevant bacteria

The present work addressed the abilities of two L-amino acid oxidases isolated from Bothrops moojeni (BmooLAAO-I) and Bothrops jararacussu (BjussuLAAO-II) snake venoms to control the growth and prevent the biofilm formation of clinically relevant bacterial pathogens. Upon S. aureus (ATCC BAA44) and S. aureus (clinical isolates), BmooLAAO-I (MIC = 0.12 and 0.24 μg/mL, respectively) and BjussuLAAO-II (MIC = 0.15 μg/mL) showed a potent bacteriostatic effect. Against E. coli (ATCC BAA198) and E. coli (clinical isolates), BmooLAAO-I (MIC = 15.6 and 62.5 μg/mL, respectively) and BjussuLAAO-II (MIC = 4.88 and 9.76 μg/mL, respectively) presented a lower extent effect. Also, BmooLAAO-I (MICB50 = 0.195 μg/mL) and BjussuLAAO-II (MICB50 = 0.39 μg/mL) inhibited the biofilm formation of S. aureus (clinical isolates) in 88% and 89%, respectively, and in 89% and 53% of E. coli (clinical isolates). Moreover, scanning electron microscopy confirmed that the toxins affected bacterial morphology by increasing the roughness of the cell surface and inhibited the biofilm formation. Furthermore, analysis of the tridimensional structures of the toxins showed that the surface-charge distribution presents a remarkable positive region close to the glycosylation motif, which is more pronounced in BmooLAAO-I than BjussuLAAO-II. This region may assist the interaction with bacterial and biofilm surfaces. Collectively, our findings propose that venom-derived antibiofilm agents are promising biotechnological tools which could provide novel strategies for biofilm-associated infections.

Unravelling the Gastroprotective Potential of Kefir: Exploring Antioxidant Effects in Preventing Gastric Ulcers

The present study was conducted to evaluate the protective effect of milk kefir against NSAID-induced gastric ulcers. Male Swiss mice were divided into three groups: control (Vehicle; UHT milk at a dose of 0.3 mL/100 g), proton pump inhibitor (PPI; lansoprazole 30 mg/kg), and 4% milk kefir (Kefir; 0.3 mL/100 g). After 14 days of treatment, gastric ulcer was induced by oral administration of indomethacin (40 mg/kg). Reactive oxygen species (ROS), nitric oxide (NO), DNA content, cellular apoptosis, IL-10 and TNF-α levels, and myeloperoxidase (MPO) enzyme activity were determined. The interaction networks between NADPH oxidase 2 and kefir peptides 1-35 were determined using the Residue Interaction Network Generator (RING) webserver. Pretreatment with kefir for 14 days prevented gastric lesions. In addition, kefir administration reduced ROS production, DNA fragmentation, apoptosis, and TNF-α systemic levels. Simultaneously, kefir increased NO bioavailability in gastric cells and IL-10 systemic levels. A total of 35 kefir peptides showed affinity with NADPH oxidase 2. These findings suggest that the gastroprotective effect of kefir is due to its antioxidant and anti-inflammatory properties. Kefir could be a promising natural therapy for gastric ulcers, opening new perspectives for future research.

ADDovenom: Thermostable Protein-Based ADDomer Nanoparticles as New Therapeutics for Snakebite Envenoming

Snakebite envenoming can be a life-threatening medical emergency that requires prompt medical intervention to neutralise the effects of venom toxins. Each year up to 138,000 people die from snakebites and threefold more victims suffer life-altering disabilities. The current treatment of snakebite relies solely on antivenom-polyclonal antibodies isolated from the plasma of hyperimmunised animals-which is associated with numerous deficiencies. The ADDovenom project seeks to deliver a novel snakebite therapy, through the use of an innovative protein-based scaffold as a next-generation antivenom. The ADDomer is a megadalton-sized, thermostable synthetic nanoparticle derived from the adenovirus penton base protein; it has 60 high-avidity binding sites to neutralise venom toxins. Here, we outline our experimental strategies to achieve this goal using state-of-the-art protein engineering, expression technology and mass spectrometry, as well as in vitro and in vivo venom neutralisation assays. We anticipate that the approaches described here will produce antivenom with unparalleled efficacy, safety and affordability.

Oxidative stress induced by Pollonein-LAAO, a new L-amino acid oxidase from Bothrops moojeni venom, prompts prostate tumor spheroid cell death and impairs the cellular invasion process in vitro

Cancer cells produce abnormal levels of reactive oxygen species (ROS) that contribute to promote their malignant phenotype. In this framework, we hypothesized that the change in ROS concentration above threshold could impair key events of prostate cancer cells (PC-3) progression. Our results demonstrated that Pollonein-LAAO, a new L-amino acid oxidase obtained from Bothrops moojeni venom, was cytotoxic to PC-3 cells in two-dimensional and in tumor spheroid assays. Pollonein-LAAO was able to increase the intracellular ROS generation that culminates in cell death from apoptosis by both intrinsic and extrinsic pathways due to the up-regulation of TP53, BAX, BAD, TNFRSF10B and CASP8. Additionally, Pollonein-LAAO reduced mitochondrial membrane potential and caused G0/G1 phase to delay, due to the up-regulation of CDKN1A and the down-regulation of the expression of CDK2 and E2F. Interestingly, Pollonein-LAAO inhibited critical steps of the cellular invasion process (migration, invasion and adhesion), due to the down-regulation of SNAI1, VIM, MMP2, ITGA2, ITGAV and ITGB3. Furthermore, the Pollonein-LAAO effects were associated with the intracellular ROS production, since the presence of catalase restored the invasiveness of PC-3 cells. In this sense, this study contributes to the potential use of Pollonein-LAAO as ROS-based agent to enhance the current understanding of cancer treatment strategies.

Next-Generation Sequencing for Venomics: Application of Multi-Enzymatic Limited Digestion for Inventorying the Snake Venom Arsenal

To improve the characterization of snake venom protein profiles, we report the application of a new generation of proteomic methodology to deeply characterize complex protein mixtures. The new approach, combining a synergic multi-enzymatic and a time-limited digestion (MELD), is a versatile and straightforward protocol previously developed by our group. The higher number of overlapping peptides generated during MELD increases the quality of downstream peptide sequencing and of protein identification. In this context, this work aims at applying the MELD strategy to a venomics purpose for the first time, and especially for the characterization of snake venoms. We used four venoms as the test models for this proof of concept: two Elapidae (Dendroaspis polylepis and Naja naja) and two Viperidae (Bitis arietans and Echis ocellatus). Each venom was reduced and alkylated before being submitted to two different protocols: the classical bottom-up proteomics strategy including a digestion step with trypsin only, or MELD, which combines the activities of trypsin, Glu-C and chymotrypsin with a limited digestion approach. The resulting samples were then injected on an M-Class chromatographic system, and hyphenated to a Q-Exactive Mass Spectrometer. Toxins and protein identification were performed by Peaks Studio X+. The results show that MELD considerably improves the number of sequenced (de novo) peptides and identified peptides from protein databases, leading to the unambiguous identification of a greater number of toxins and proteins. For each venom, MELD was successful, not only in terms of the identification of the major toxins (increasing of sequence coverage), but also concerning the less abundant cellular components (identification of new groups of proteins). In light of these results, MELD represents a credible methodology to be applied as the next generation of proteomics approaches dedicated to venomic analysis. It may open new perspectives for the sequencing and inventorying of the venom arsenal and should expand global knowledge about venom composition.

Biochemical characterization and assessment of leishmanicidal effects of a new L-amino acid oxidase from Crotalus durissus collilineatus snake venom (CollinLA AO-I)

This study reports the isolation of CollinLAAO-I, a new L-amino acid oxidase from Crotalus durissus collilineatus snake venom, its biochemical characterization and leishmanicidal potential in Leishmania spp. CollinLAAO-I (63.1 kDa) was successfully isolated with high purity using two chromatographic steps and represents 2.5% of total venom proteins. CollinLAAO-I displayed high enzymatic activity (4262.83 U/mg/min), significantly reducing after 28 days. The enzymatic activity of CollinLAAO-I revealed higher affinity for hydrophobic amino acids such as L-leucine, high enzymatic activity in a wide pH range (6.0-10.0), at temperatures from 0 to 25 °C, and showed complete inhibition in the presence of Na⁺ and K⁺. Cytotoxicity assays revealed IC₅₀ of 18.49 and 11.66 μg/mL for Leishmania (L.) amazonensis and Leishmania (L.) infantum, respectively, and the cytotoxicity was completely suppressed by catalase. CollinLAAO-I significantly increased the intracellular concentration of reactive oxygen species (ROS) and reduced the mitochondrial potential of both Leishmania species. Furthermore, CollinLAAO-I decreased the parasite capacity to infect macrophages by around 70%, indicating that even subtoxic concentrations of CollinLAAO-I can interfere with Leishmania vital processes. Thus, the results obtained for CollinLAAO-I provide important support for developing therapeutic strategies against leishmaniasis.

Isolation and characterization of the first phosphodiesterase (Bj-PDE) from the venom of Bothrops jararacussu snake

Phosphodiesterases are exonucleases that sequentially hydrolyse phosphodiester bonds of polynucleotides from the 3'-end and release 5-mononucleotides. After more than one decade without any advance in the study of Bothropic phosphodiesterases, we described here the isolation of the first phosphodiesterase from Bothrops jararacussu, which we named Bj-PDE. A five-step column chromatography procedure (size exclusion, hydrophobic interaction, cation exchange, lentil lectin affinity, and blue sepharose affinity) enabled isolation of Bj-PDE with preserved and stable enzymatic activity (bis(p-nitrophenyl) phosphate substrate), K_m = 6.9 mM (± 0.7 mM), k_cat/K_m = 1.7 × 10⁴ M^-1 s^-1 (± 0.2 × 10⁴ M^-1 s^-1), MW = 116 kDa (SDS-PAGE), optimum activity around 45 °C at pH 8.0, and stability for 81 days at different storage temperatures (8, -20, and - 80 °C). Ca²⁺ and Mg²⁺ ions positively influenced Bj-PDE activity, while EDTA had the opposite action. Zn²⁺ restored >50 % of enzyme activity after its inhibition by EDTA. The Bj-PDE partial sequence identified by mass spectrometry was very similar to the sequence of BATXPDE1 from Bothrops atrox, which was evolutionarily close to this new PDE. Therefore, our study represents an important progress on the isolation of this minor toxin and sheds new lights on the properties and bioprospection of bothropic phosphodiesterases.

Heterologous expression of Ts8, a neurotoxin from Tityus serrulatus venom, evidences its antifungal activity

In this study we expressed the Ts8, a neurotoxin from Tityus serrulatus scorpion venom, in Pichia pastoris yeast. We evaluated the peptide expression in different conditions, such as pH, temperature, and addition of casamino acids supplement. Analyses of expressed products by mass spectrometry and Edman degradation showed that rTs8 has sites that allow its cleavage by yeast proteases released into the culture medium. The casamino acids addition was favourable for toxin expression, however, was not sufficient to minimize proteolytic degradation. Functional assays with recombinant toxin fragments and native toxins have demonstrated the release of cytokines such as TNF-α and IL-1β in some peptides tested. In addition, the toxins were shown to inhibit the Pichia pastoris growth in antifungal test and were not toxic to alveolar macrophages cells at the concentrations analyzed The electrophysiological screening, by voltage clamp technique, showed that the rTs8 fragment with the highest molecular weight inhibited the Kv1.3 channel, whereas the N-terminal fragment had no activity on the ion channels tested.

Use of kefir peptide (Kef-1) as an emerging approach for the treatment of oxidative stress and inflammation in 2K1C mice

The benefits of kefir consumption are partially due to the rich composition of bioactive molecules released from its fermentation. Angiotensin-converting enzyme (ACE) inhibitors are bioactive molecules with potential use in the treatment or prevention of hypertension, heart failure, and myocardial infarction. Here, the in vivo actions of the Kef-1 peptide, an ACE inhibitor derived from kefir, were evaluated in an angiotensin II-dependent hypertension model. The Kef-1 peptide showed a potential anti-hypertensive effect. Additionally, Kef-1 exhibited systemic antioxidant and anti-inflammatory activities. In smooth muscle cells (SMCs), the Kef-1 peptide decreased ROS production through the reduced participation of NADPH oxidase and mitochondria. The aorta of 2K1C mice treated with Kef-1 showed lesser wall-thickening and partial restoration of the endothelial structure. In conclusion, these novel findings highlight the in vivo biological potential of this peptide demonstrating that Kef-1 may be a relevant nutraceutical treatment for cardiovascular diseases.

De Novo Transcriptome Analysis of the Venom of Latrodectus geometricus with the Discovery of an Insect-Selective Na Channel Modulator

The brown widow spider, Latrodectus geometricus, is a predator of a variety of agricultural insects and is also hazardous for humans. Its venom is a true pharmacopeia representing neurotoxic peptides targeting the ion channels and/or receptors of both vertebrates and invertebrates. The lack of transcriptomic information, however, limits our knowledge of the diversity of components present in its venom. The purpose of this study was two-fold: (1) carry out a transcriptomic analysis of the venom, and (2) investigate the bioactivity of the venom using an electrophysiological bioassay. From 32,505 assembled transcripts, 8 toxin families were classified, and the ankyrin repeats (ANK), agatoxin, centipede toxin, ctenitoxin, lycotoxin, scorpion toxin-like, and SCP families were reported in the L. geometricus venom gland. The diversity of L. geometricus venom was also uncovered by the transcriptomics approach with the presence of defensins, chitinases, translationally controlled tumor proteins (TCTPs), leucine-rich proteins, serine proteases, and other important venom components. The venom was also chromatographically purified, and the activity contained in the fractions was investigated using an electrophysiological bioassay with the use of a voltage clamp on ion channels in order to find if the neurotoxic effects of the spider venom could be linked to a particular molecular target. The findings show that U24-ctenitoxin-Pn1a involves the inhibition of the insect sodium (Na_v) channels, BgNa_v and DmNa_v. This study provides an overview of the molecular diversity of L. geometricus venom, which can be used as a reference for the venom of other spider species. The venom composition profile also increases our knowledge for the development of novel insecticides targeting voltage-gated sodium channels.

A comparative study on the leishmanicidal activity of the L-amino acid oxidases BjussuLAAO-II and BmooLAAO-II isolated from Brazilian Bothrops snake venoms

This study aims to examine whether two L-amino acid oxidases isolated from Bothrops snake venom (SV-LAAOs) were cytotoxic to Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis, two causative agents of leishmaniasis, which is an endemic disease in tropical and subtropical countries. The SV-LAAOs BjussuLAAO-II and BmooLAAO-II were isolated from Bothrops jararacussu and Bothrops moojeni venom, respectively, through a three-step chromatography process that used molecular exclusion, hydrophobic interaction, and affinity columns. BmooLAAO-II is a new SV-LAAO isoform that we isolated in this study. The purified BjussuLAAO-II and BmooLAAO-II had high L-amino acid oxidase-specific activity: 3481.17 and 4924.77 U/mg/min, respectively. Both SV-LAAOs were strongly cytotoxic to the two Leishmania species, even at low concentrations. At the same concentration, BjussuLAAO-II and BmooLAAO-II exerted different cytotoxic effects on the parasites. We reported for the first time that the SV-LAAOs suppressed cell proliferation and altered the mitochondrial membrane potential of the two Leishmania species. Surprisingly, BjussuLAAO-II increased the intracellular reactive oxygen species production only in L. (L.) amazonensis, while BmooLAAO-II increased the intracellular reactive oxygen species production only in L. (V.) braziliensis, indicating that these SV-LAAOs had a certain specificity of action.

Decellularized Splenic Matrix as a Scaffold for Spleen Bioengineering

The spleen is considered a non-essential organ. However, its importance is increasingly clear, given the serious disorders caused by its absence or dysfunction, e.g., greater susceptibility to infections, thromboembolism and cancer. Surgical techniques to preserve the spleen and maintain splenic function have become increasingly common. However, the morbidity and mortality associated with its absence and dysfunction are still high. We used the decellularization technique to obtain a viable splenic scaffold for recellularization in vitro and propose the idea of bioengineered spleen transplantation to the host. We observed the maintenance of important structural components such as white pulp, marginal zone and red pulp, in addition to the network of vascular ducts. The decellularized scaffold presents minimal residual DNA and SDS, which are essential to prevent immunogenic responses and transplantation failure. Also, the main components of the splenic matrix were preserved after decellularization, with retention of approximately 72% in the matrisomal protein content. The scaffold we developed was partially recellularized with stromal cells from the spleen of neonatal rats, demonstrating adhesion, proliferation and viability of cells. Therefore, the splenic scaffold is very promising for use in studies on spleen reconstruction and transplantation, with the aim of complete recovery of splenic function.

Sildenafil attenuates nonsteroidal anti-inflammatory-induced gastric ulceration in mice via antioxidant and antigenotoxic mechanisms

Sildenafil (SIL) has potential as an interesting gastroprotective drug. However, the pathways of its protective effect still needs to be clarified, and its use as a potential gastroprotective agent validated. This study aims to evaluate the effects of SIL via modulation of oxidative stress in a NSAID-induced gastric lesion model. Male Swiss mice were divided into six groups: control (CON, water), nonsteroidal anti-inflammatory drug (NSAID, water), proton pump inhibitor (PPI, 30 mg/kg of lansoprazole), SIL 5 (5 mg/kg), SIL 25 (25 mg/kg) and SIL 50 (50 mg/kg). The animals were treated by gavage (a single dose) after 24 hours of fasting, and gastric lesions were performed after 30 minutes, with indomethacin (40 mg/kg, by gavage). After 6h, the animals were killed and the stomach was removed to evaluate reactive oxygen species (ROS) production, oxidation of macromolecules, quantification of antioxidant enzymes, DNA fragmentation, apoptosis and macroscopic and histologic analysis of gastric lesions. SIL exerts a dose-dependent gastroprotective effect against NSAID-induced mucosal injury, also reducing cytoplasmic levels of ROS and consequent oxidative damage to macromolecules. In addition, SIL increases nitric oxide bioavailability, antioxidant enzymes and gastric cellular viability, as well as restoring important factors involved in gastroprotection. Our results demonstrate that different doses of SIL prevent indomethacin-induced gastric ulcer in mice via different, but complementary antioxidant, antigenotoxic and antiapoptotic mechanisms.

From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery

Animal poisons and venoms are comprised of different classes of molecules displaying wide-ranging pharmacological activities. This review aims to provide an in-depth view of toxin-based compounds from terrestrial and marine organisms used as diagnostic tools, experimental molecules to validate postulated therapeutic targets, drug libraries, prototypes for the design of drugs, cosmeceuticals, and therapeutic agents. However, making these molecules applicable requires extensive preclinical trials, with some applications also demanding clinical trials, in order to validate their molecular target, mechanism of action, effective dose, potential adverse effects, as well as other fundamental parameters. Here we go through the pitfalls for a toxin-based potential therapeutic drug to become eligible for clinical trials and marketing. The manuscript also presents an overview of the current picture for several molecules from different animal venoms and poisons (such as those from amphibians, cone snails, hymenopterans, scorpions, sea anemones, snakes, spiders, tetraodontiformes, bats, and shrews) that have been used in clinical trials. Advances and perspectives on the therapeutic potential of molecules from other underexploited animals, such as caterpillars and ticks, are also reported. The challenges faced during the lengthy and costly preclinical and clinical studies and how to overcome these hindrances are also discussed for that drug candidates going to the bedside. It covers most of the drugs developed using toxins, the molecules that have failed and those that are currently in clinical trials. The article presents a detailed overview of toxins that have been used as therapeutic agents, including their discovery, formulation, dosage, indications, main adverse effects, and pregnancy and breastfeeding prescription warnings. Toxins in diagnosis, as well as cosmeceuticals and atypical therapies (bee venom and leech therapies) are also reported. The level of cumulative and detailed information provided in this review may help pharmacists, physicians, biotechnologists, pharmacologists, and scientists interested in toxinology, drug discovery, and development of toxin-based products.

Proteome of fraction from Tityus serrulatus venom reveals new enzymes and toxins

Background

Tityus serrulatus venom (Ts venom) is a complex mixture of several compounds with biotechnological and therapeutical potentials, which highlights the importance of the identification and characterization of these components. Although a considerable number of studies have been dedicated to the characterization of this complex cocktail, there is still a limitation of knowledge concerning its venom composition. Most of Ts venom studies aim to isolate and characterize their neurotoxins, which are small, basic proteins and are eluted with high buffer concentrations on cation exchange chromatography. The first and largest fraction from carboxymethyl cellulose-52 (CMC-52) chromatography of Ts venom, named fraction I (Fr I), is a mixture of proteins of high and low molecular masses, which do not interact with the cation exchange resin, being therefore a probable source of components still unknown of this venom. Thus, the present study aimed to perform the proteome study of Fraction I from Ts venom, by high resolution mass spectrometry, and its biochemical characterization, by the determination of several enzymatic activities.

Methods

Fraction I was obtained by a cation exchange chromatography using 50 mg of crude venom. This fraction was subjected to a biochemical characterization, including determination of L-amino acid oxidase, phospholipase, hyaluronidase, proteases activities and inhibition of angiotensin converting enzyme (ACE) activity. Fraction I was submitted to reduction, alkylation and digestion processes, and the tryptic digested peptides obtained were analyzed in a Q-Exactive Orbitrap mass spectrometer. Data analysis was performed by PEAKS 8.5 software against NCBI database.

Results

Fraction I exhibits proteolytic activity and it was able to inhibit ACE activity. Its proteome analysis identified 8 different classes of venom components, among them: neurotoxins (48%), metalloproteinases (21%), hypotensive peptides (11%), cysteine-rich venom protein (9%), antimicrobial peptides (AMP), phospholipases and other enzymes (chymotrypsin and lysozymes) (3%) and phosphodiesterases (2%).

Conclusions

The combination of a proteomic and biochemical characterization strategies leads us to identify new components in the T. serrulatus scorpion venom. The proteome of venom´s fraction can provide valuable direction in the obtainment of components in their native forms in order to perform a preliminary characterization and, consequently, to promote advances in biological discoveries in toxinology.

Microbial production of toxins from the scorpion venom: properties and applications

Scorpion venom are composed mainly of bioactive proteins and peptides that may serve as lead compounds for the design of biotechnological tools and therapeutic drugs. However, exploring the therapeutic potential of scorpion venom components is mainly impaired by the low yield of purified toxins from milked venom. Therefore, production of toxin-derived peptides and proteins by heterologous expression is the strategy of choice for research groups and pharmaceutical industry to overcome this limitation. Recombinant expression in microorganisms is often the first choice, since bacteria and yeast systems combine high level of recombinant protein expression, fast cell growth and multiplication and simple media requirement. Herein, we present a comprehensive revision, which describes the scorpion venom components that were produced in their recombinant forms using microbial systems. In addition, we highlight the pros and cons of performing the heterologous expression of these compounds, regarding the particularities of each microorganism and how these processes can affect the application of these venom components. The most used microbial system in the heterologous expression of scorpion venom components is Escherichia coli (85%), and among all the recombinant venom components produced, 69% were neurotoxins. This review may light up future researchers in the choice of the best expression system to produce scorpion venom components of interest.

Non-disulfide-bridged peptides from Tityus serrulatus venom: Evidence for proline-free ACE-inhibitors

The present study purifies two T. serrulatus non-disulfide-bridged peptides (NDBPs), named venom peptides 7.2 (RLRSKG) and 8 (KIWRS) and details their synthesis and biological activity, comparing to the synthetic venom peptide 7.1 (RLRSKGKK), previously identified. The synthetic replicate peptides were subjected to a range of biological assays: hemolytic, antifungal, antiviral, electrophysiological, immunological and angiotensin-converting enzyme (ACE) inhibition activities. All venom peptides neither showed to be cytolytic nor demonstrated significant antifungal or antiviral activities. Interestingly, peptides were able to modulate macrophages' responses, increasing IL-6 production. The three venom peptides also demonstrated potential to inhibit ACE in the following order: 7.2>7.1>8. The ACE inhibition activity was unexpected, since peptides that display this function are usually proline-rich peptides. In attempt to understand the origin of such small peptides, we discovered that the isolated peptides 7.2 and 8 are fragments of the same molecule, named Pape peptide precursor. Furthermore, the study discusses that Pape fragments could be originated from a post-splitting mechanism resulting from metalloserrulases and other proteinases cleavage, which can be seen as a clever mechanism used by the scorpion to enlarge its repertoire of venom components. Scorpion venom remains as an interesting source of bioactive proteins and this study advances our knowledge about three NDBPs and their biological activities.

Isolation and characterization of Ts19 Fragment II, a new long-chain potassium channel toxin from Tityus serrulatus venom

Ts19 Fragment II (Ts19 Frag-II) was first isolated from the venom of the scorpion Tityus serrulatus (Ts). It is a protein presenting 49 amino acid residues, three disulfide bridges, Mr 5534Da and was classified as a new member of class (subfamily) 2 of the β-KTxs, the second one described for Ts scorpion. The β-KTx family is composed by two-domain peptides: N-terminal helical domain (NHD), with cytolytic activity, and a C-terminal CSαβ domain (CCD), with Kv blocking activity. The extensive electrophysiological screening (16 Kv channels and 5 Nav channels) showed that Ts19 Frag-II presents a specific and significant blocking effect on Kv1.2 (IC50 value of 544±32nM). However, no cytolytic activity was observed with this toxin. We conclude that the absence of 9 amino acid residues from the N-terminal sequence (compared to Ts19 Frag-I) is responsible for the absence of cytolytic activity. In order to prove this hypothesis, we synthesized the peptide with these 9 amino acid residues, called Ts19 Frag-III. As expected, Ts19 Frag-III showed to be cytolytic and did not block the Kv1.2 channel. The post-translational modifications of Ts19 and its fragments (I-III) are also discussed here. A mechanism of post-translational processing (post-splitting) is suggested to explain Ts19 fragments production. In addition to the discovery of this new toxin, this report provides further evidence for the existence of several compounds in the scorpion venom contributing to the diversity of the venom arsenal.

Influence of post-starvation extraction time and prey-specific diet in Tityus serrulatus scorpion venom composition and hyaluronidase activity

The role of diet in venom composition has been a topic of intense research interest. This work presents evidence that the variation in the venom composition from the scorpion Tityus serrulatus (Ts) is closely associated with post-starvation extraction time and prey-specific diet. The scorpions were fed with cockroach, cricket, peanut beetle or giant Tenebrio. The venoms demonstrated a pronounced difference in the total protein and toxins composition, which was evaluated by electrophoresis, reversed-phase chromatography, densitometry, hyaluronidase activity and N-terminal sequencing. Indeed, many toxins and peptides, such as Ts1, Ts2, Ts4, Ts5, Ts6, Ts15, Ts19 frag. II, hypotensins 1 and 3, PAPE peptide and peptide 9797 (first described in Ts venom), were all identified in different proportions in the analyzed Ts venoms. This study is pioneer on assessing the influence of the starvation time and the prey diet on hyaluronidase activity as well as to describe a modification of Tricine-gel-electrophoresis to evaluate this enzyme activity. Altogether, this study reveal a large contribution of the extraction time and diet on Ts venom variability as well as present a background to recommend the cockroach diet to obtain higher protein content and the cricket diet to obtain higher hyaluronidase specific activity.

Association of interleukin-6 gene polymorphism with angina pectoris

In this study, we investigated the role of the -174G>C polymorphism of interleukin-6 (IL-6) as a predisposing factor to angina pectoris. Patients were separated into 2 groups: angina (N = 72) and nonangina (N = 71). There were no statistical differences between groups for all cardiovascular risk factors evaluated. The GG genotype frequency was 18% lower in the angina than in the non-angina group, whereas GC + CC was 18% higher in the angina group (P = .036). The frequency of G allele was 11% lower in the angina than in the nonangina group and C allele was 11% higher in the angina group (P = .043). Patients carrying the C allele showed a 2-fold increased risk for angina pectoris (P = .036). Our study demonstrates a high incidence of the -174G>C polymorphism of the IL-6 gene in patients with angina pectoris compared with those carrying the G allele, reinforcing the contribution of genetic factors to the symptoms of angina pectoris.