Bradykinin-potentiating Peptides Research Articles

Structural Characterization and Rat Aortic Vascular Reactivity of Bradykinin-Potentiating Peptides (BPPs) from the Snake Venom of Bothrops moojeni from Delta do Parnaíba Region, Brazil.

Snake venoms contain various bradykinin-potentiating peptides (BPPs). First studied for their vasorelaxant properties due to angiotensin converting enzyme (ACE) inhibition, these molecules present a range of binding partners, among them the argininosuccinate synthase (AsS) enzyme. This has renewed interest in their characterization from biological sources and the evaluation of their pharmacological activities. In the present work, the low molecular weight fraction of Bothrops moojeni venom was obtained and BPPs were characterized by mass spectrometry. Eleven BPPs or related peptides were sequenced, and one of them, BPP-Bm01, was new. Interestingly, some oxidized BPPs were detected. The three most abundant peptides were BPP-Bm01, BPP-Bax12, and BPP-13a, and their putative interactions with the AsS enzyme were investigated in silico. A binding cavity for these molecules was predicted, and docking studies allowed their ranking. Three peptides were synthesized and submitted to vasorelaxation assays using rat aortic rings. While all BPPs were active, BPP-Bm01 showed the highest potency in this assay. This work adds further diversity to BPPs from snake venoms and suggests, for the first time, a putative binding pocket for these molecules in the AsS enzyme. This can guide the design of new and more potent AsS activators.

Unveiling the peptidome diversity of Lachesismuta snake venom: Discovery of novel fragments of metalloproteinase, l-amino acid oxidase, and bradykinin potentiating peptides

Snake venoms are known to be major sources of peptides with different pharmacological properties. In this study, we comprehensively explored the venom peptidomes of three specimens of Lachesismuta, the largest venomous snake in South America, using mass spectrometry techniques. The analysis revealed 19 main chromatographic peaks common to all specimens. A total of 151 peptides were identified, including 69 from a metalloproteinase, 58 from the BPP-CNP precursor, and 24 from a l-amino acid oxidase. To our knowledge, 126 of these peptides were reported for the first time in this work, including a new SVMP-derived peptide fragment, Lm-10a. Our findings highlight the dynamic nature of toxin maturation in snake venoms, driven by proteolytic processing, post-translational modifications, and cryptide formation.

De Novo Assembly of Venom Gland Transcriptome of Tropidolaemus wagleri (Temple Pit Viper, Malaysia) and Insights into the Origin of Its Major Toxin, Waglerin.

The venom proteome of Temple Pit Viper (Tropidolaemus wagleri) is unique among pit vipers, characterized by a high abundance of a neurotoxic peptide, waglerin. To further explore the genetic diversity of its toxins, the present study de novo assembled the venom gland transcriptome of T. wagleri from west Malaysia. Among the 15 toxin gene families discovered, gene annotation and expression analysis reveal the dominating trend of bradykinin-potentiating peptide/angiotensin-converting enzyme inhibitor-C-type natriuretic peptide (BPP/ACEI-CNP, 76.19% of all-toxin transcription) in the transcriptome, followed by P-III snake venom metalloproteases (13.91%) and other toxins. The transcript TwBNP01 of BPP/ACEI-CNP represents a large precursor gene (209 amino acid residues) containing the coding region for waglerin (24 residues). TwBNP01 shows substantial sequence variations from the corresponding genes of its sister species, Tropidolaemus subannulatus of northern Philippines, and other viperid species which diversely code for proline-rich small peptides such as bradykinin-potentiating peptides (BPPs). The waglerin/waglerin-like peptides, BPPs and azemiopsin are proline-rich, evolving de novo from multiple highly diverged propeptide regions within the orthologous BPP/ACEI-CNP genes. Neofunctionalization of the peptides results in phylogenetic constraints consistent with a phenotypic dichotomy, where Tropidolaemus spp. and Azemiops feae convergently evolve a neurotoxic trait while vasoactive BPPs evolve only in other species.

Characterization of a New Hypotensive Peptide from the Venom of Snake Bothrops jararaca (Bj)

Background: Snake venom has become a key source of many bioactive peptides, enzymes, and toxins associated with blood coagulation and neuronal toxicity. In the past, a number of bradykinin potentiating peptides have been isolated from snake venom that display hypotensive activity due to their inhibitory action towards Angiotensin-Converting Enzyme (ACE). Significant interest has developed to isolate, characterize, and subsequently design peptide analogs as potent ACE-inhibitors which may find therapeutic applications for the treatment of hypertension and associated diseases. Aim: The aim of this study is to search for new bioactive peptide/s in the venom of the snake Bothrops Jararaca (Bj). Objective: The objective is to isolate and characterize new hypotensive peptides from BJ venom. Methods: We examined the venom of Bj which is known to host a range of bioactive peptides. We have isolated a new peptide (BJ-1) which displayed in vitro potent hypotensive activity. The peptide was purified via Sephadex G25 column chromatography and RP-HPLC. It was characterized by mass spectrometry, amino acid analysis, N-terminal sequencing, and chemical synthesis. Result: The peptide was identified as an octa-decapeptide with amino acid sequence as DCPSDWSSYEGHCYKPFS where the two Cys residues are likely present in free state, although they can form an internal S-S bond upon oxidation. It was fully confirmed by comparing with synthetic peptide prepared by solid phase chemistry. Both have the same molecular mass (2,108 Da) and identical bioactivity. Furthermore, we rationalize that BJ-1 may be derived from precursor protein “Coagulation factor IX/factor X binding protein (CF-IX/X-BP)” by proteolytic cleavage at the Nterminus of its B-chain within the sequence KPFS18↓E19PKN. This cleavage site contains the recognition motif of enzyme PCSK8 (Proprotein Convertase Subtilisin Kexin8) also known as Subtilisin Kexin Isozyme 1 (SKI-1) or Site 1 Protease (S1P). Despite this observation, using a synthetic peptide encompassing the proposed cleavage site and recombinant PCSK8 enzyme, we found that the enzyme responsible for generation of BJ-1 is not PCSK8. Further studies will be needed to identify the associated enzyme and fully characterize the pharmacological and biological properties of the peptide. Conclusion: Our study revealed the presence of a novel hypotensive octa-decapeptide in the venom of the snake Bothrops jararaca. It is likely derived from the A-chain of protein CF-IX/X-BP via proteolytic cleavage at the N-terminus by a protease yet to be characterized.

Comparative Study to Characterise the Pharmaceutical Potential of Synthesised Snake Venom Bradykinin-Potentiating Peptides In Vivo.

Bradykinin-potentiating peptides (BPPs) are snake venom peptides inhibiting the angiotensin-converting enzyme (ACE). ACE plays an important role in the regulation of blood pressure. BPPs lead to the development of ACE inhibitors for the treatment of hypertension. The objective of the present work was to carry out a comprehensive comparative study of four synthesised snake venom BPPs in vivo. Four synthesised snake venom BPPs were administered to rats via the intraperitoneal route for 15 days at a fixed dose. Lisinopril was used as a comparative standard. Thirty male albino rats were divided into six groups: A, B, C, D, E (lisinopril), and F (control). Group F was maintained as the control group and given only saline. After 15 days, blood samples and tissues were removed for the study of selective biochemical parameters and histomorphometric analysis. Statistical evaluation of all results was also performed. The results indicated that peptide I, with the sequence ZSAPGNEAIPP, was highly toxic and adversely affected all the biochemical and histological parameters studied in this work. Peptide II (ZNWPHPQIPP) and peptide IV (ZQWAQGRAPHPP) showed lower toxicity. None of the BPPs raised the serum creatinine level and exhibited nephroprotective effects. Although lisinopril raised the creatinine level, it showed a protective role towards the pancreas and lungs in parallel. The present work shows that although there is a high sequence similarity between the four BPPs, their in vivo activity varies. The sequences of peptide II and peptide IV can be used to improve the design of current ACE inhibitors used for hypertension treatment.

Integrated in silico-in vitro molecular modeling and design of halogenated phenylalanine-containing antihypertensive peptide inhibitors with halogen bonds to target human angiotensin-I-converting enzyme

Angiotensin-I-converting enzyme (ACE) is a key regulator of blood pressure as its critical role in the renin-angiotensin-aldosterone and kallikrein-kinin systems. Although a variety of natural and food peptides have been discovered to possess ACE-inhibitory activity over the past decades, they cannot be directly used as drugs due to their low efficiency and bad bioavailability. In this study, the intermolecular interaction of ACE with a snake venom inhibitor of bradykinin potentiating peptide b (BPPb) was investigated systematically at structural and energetic levels. The C-terminal region of the peptide can tightly pack against the enzyme active site and is primarily responsible for the enzyme inhibition. A tetrapeptide that covers the C-terminal region of BPPb exhibited a satisfactory ACE-inhibitory profile, which was used as start to generate a number of phenylalanine (Phe)-containing antihypertensive peptide inhibitors. The ortho-, meta- and para-positions of peptide Phe−2 phenyl moiety were systematically substituted with halogen atoms. It is revealed that bromine substitution separately at the meta- and para-positions can considerably improve the peptide inhibitory activity by 7.6-fold and 3.7-fold by forming a bifurcated halogen-bonding system with ACE His513 and Val518 residues as well as a binary halogen-bonding system with ACE Glu384 residue, respectively.

Inhibition of argininosuccinate synthase (ASS) affected ammonia excretion in yellow catfish Pelteobagrus fulvidraco during acute ammonia poisoning

Ammonia is toxic to most fish. Different fish have different treatment methods for ammonia toxicity, mainly including urea cycle and glutamine synthesis pathway, depending on their physiological status. A two-stage study was carried out to test the inhibition of argininosuccinate synthase (ASS) effects on ammonia detoxification in hyperammonemia yellow catfish. At the stage 1, fish were injected lethal half concentration (LC50) of ammonium acetate and sampled at 0, 1, 3, 6, 12 and 24 h post-injection. The result found that plasma ammonia content of fish was injected with ammonium acetate reached its highest level at hour 1, which was used as the optimal sampling time in stage 2. At the stage 2, the four experimental groups were carried out: NaCl group was injected intraperitoneally with 0.9% sodium chloride as control; NH3 group was injected with LC50 ammonium acetate; NH3+BPP group was injected with mixture of ammonium acetate and bradykinin-potentiating peptide (BPP); BPP group was injected with BPP. The results showed that inhibition of ASS can lead to accumulation of ammonia in plasma and kidney, and glutamine in liver and kidney; and decreases ASS, argininosuccinate lyase, arginase activates, and ornithine, glutamate, alanine, proline, tyrosine, methionine contents, and increases ornithine transcarbamylase, glutaminase activates, and citrulline, aspartate, arginine, glutamine, histidine, isoleucine, phenylalanine, lysine contents; and result in upregulation of ASS, ASL, CPS 1, OTC, GS and GLS genes expression. This result indicates that the inhibition of ASS in yellow catfish with ammonia poisoning will lead to the urea cycle disorder; yellow catfish can enhance the detoxification capacity of ammonia by improving glutamine synthesis when the urea cycle is inhibited; argininase played an important role in ammonia detoxification of yellow catfish.

Expanding the neutralization scope of the Central American antivenom (PoliVal-ICP) to include the venom of Crotalus durissus pifanorum

The proteomic, enzymatic, toxicological, and immunogenic profiles of the venom of C. d. pifanorum were studied. It was found that venom of C. d. pifanorum is composed of 63% phospholipases A2 (PLA2s), 13% serine proteinases (SVSPs), 8% bradykinin-potentiating peptides (BPPs), 4% L-amino acid oxidases (LAAOs), 3% metalloproteinases (SVMPs), and other minor components. This composition allows the venom to exert lethal, PLA2, myotoxic, coagulant and defibrinogenating activities, but no azocaseinolytic or hemorrhagic activities. The addition of C. d. pifanorum venom to the group of venoms used as immunogens to produce the Central American antivenom PoliVal-ICP (i.e., venoms of Bothrops asper, Crotalus simus and Lachesis stenophrys) resulted in 1) the expansion of the neutralization scope of the antivenom to cover the venom of C. d. pifanorum and other antigenically related venom (i.e., C. s. scutulatus venom), 2) improvement of the neutralizing potency towards the venom of C. simus, and 3) no significant reduction of the neutralization of venoms of B. asper and L. stenophrys. It was concluded that supplementation of the immunogens used to produce PoliVal-ICP with the venom of C. d. pifanorum is a viable alternative to expand the neutralization scope of the antivenom. Biological significanceThe venom of Crotalus durissus pifanorum from Venezuela has a proteomic profile like those of other subspecies of the South American rattlesnake C. durissus, with predominance of phospholipases A2 (especially crotoxin) and serine proteinases. This explains a toxicological profile characterized by neurotoxicity, myotoxicity, and coagulopathies, but being devoid of hemorrhagic activity. The antivenom used in Central America (PoliVal-ICP) includes the venom of C. simus, which has a different composition, in the immunizing strategy. Accordingly, this antivenom does not neutralize C. d. pifanorum venom. The addition of C. d. pifanorum venom to the immunizing mixture of PoliVal-ICP expands the neutralizing scope of this antivenom, to cover additional rattlesnake venoms, while not affecting the response to C. simus, Bothrops asper and Lachesis stenophrys venoms. This represents an improvement of the current PoliVal-ICP.

Tracking the recruitment and evolution of snake toxins using the evolutionary context provided by the Bothrops jararaca genome

Venom is a key adaptive innovation in snakes, and how nonvenom genes were co-opted to become part of the toxin arsenal is a significant evolutionary question. While this process has been investigated through the phylogenetic reconstruction of toxin sequences, evidence provided by the genomic context of toxin genes remains less explored. To investigate the process of toxin recruitment, we sequenced the genome of Bothrops jararaca, a clinically relevant pitviper. In addition to producing a road map with canonical structures of genes encoding 12 toxin families, we inferred most of the ancestral genes for their loci. We found evidence that 1) snake venom metalloproteinases (SVMPs) and phospholipases A2 (PLA2) have expanded in genomic proximity to their nonvenomous ancestors; 2) serine proteinases arose by co-opting a local gene that also gave rise to lizard gilatoxins and then expanded; 3) the bradykinin-potentiating peptides originated from a C-type natriuretic peptide gene backbone; and 4) VEGF-F was co-opted from a PGF-like gene and not from VEGF-A. We evaluated two scenarios for the original recruitment of nontoxin genes for snake venom: 1) in locus ancestral gene duplication and 2) in locus ancestral gene direct co-option. The first explains the origins of two important toxins (SVMP and PLA2), while the second explains the emergence of a greater number of venom components. Overall, our results support the idea of a locally assembled venom arsenal in which the most clinically relevant toxin families expanded through posterior gene duplications, regardless of whether they originated by duplication or gene co-option.

The venom of the Lebanese viper, Montivipera bornmuelleri contains vasoactive compounds

Snake venoms are rich mixtures of polypeptides, which target, among other physiological networks, the cardiovascular system. Snake toxins such as phospholipase A2 (PLA2), natriuretic peptides (NPs), and bradykinin-potentiating peptides (BPP) exert various effects with vascular consequences (hypotension, vasorelaxation…). Some of these toxins have been developped as drugs with antihypertensive properties, such as Captopril™. We have previously shown that the venom of Montivipera bornmuelleri induces the relaxation of rat aortic rings. Here, we aim to identify and characterize the vasoactive compounds of this venom. The venom was fractionated by HPLC. The fractions were assayed on the endothelial cell line, Mile Sven 1 (MS1) and two different cell lines, which stably expressed muscarinic receptors M1 and M3. We screened for compounds able to inhibit acetylcholine-induced intracellular Ca 2+ rise, using the fluorescence probe FURA-2. Wire myography on isolated mesenteric arteries was used. Proteomic analysis was performed to characterize selected fractions. Among 23 fractions of the M. bornmuelleri venom, one fraction was selected for its ability to reduce acetylcholine-induced Ca 2+ rise in MS1 cells. The proteomic analysis led to identify a novel peptidyl toxin, homologous to a vascular endothelial growth factor toxin from Macrovipera lebetina . However, this novel toxin was unable to antagonize acetylcholine-induced Ca 2+ rise in cells expressing muscarinic receptors M1 or M3, suggesting that this peptide acts indirectly on the Ca 2+ signaling pathway in endothelial cells. In myography, the crude venom exhibited a vasorelaxant effect on mesenteric arteries, but the isolated peptide did not. The M. bornmuelleri venom exerts a vasorelaxant effect on mesenteric arteries. We found a novel toxin homologous to a vascular endothelial growth factor snake toxin, which modulates Ca 2+ signaling pathway in endothelial cells.

Snake Venom Components: Tools and Cures to Target Cardiovascular Diseases.

Cardiovascular diseases (CVDs) are considered as a major cause of death worldwide. Therefore, identifying and developing therapeutic strategies to treat and reduce the prevalence of CVDs is a major medical challenge. Several drugs used for the treatment of CVDs, such as captopril, emerged from natural products, namely snake venoms. These venoms are complex mixtures of bioactive molecules, which, among other physiological networks, target the cardiovascular system, leading to them being considered in the development and design of new drugs. In this review, we describe some snake venom molecules targeting the cardiovascular system such as phospholipase A2 (PLA2), natriuretic peptides (NPs), bradykinin-potentiating peptides (BPPs), cysteine-rich secretory proteins (CRISPs), disintegrins, fibrinolytic enzymes, and three-finger toxins (3FTXs). In addition, their molecular targets, and mechanisms of action—vasorelaxation, inhibition of platelet aggregation, cardioprotective activities—are discussed. The dissection of their biological effects at the molecular scale give insights for the development of future snake venom-derived drugs.

Snake Venom Toxins: Clinical use and as Diagnostic Agents

Snakes are fascinating creatures and were inhabitants of this world well before the earth was populated by ancient humans. Snakes with a lethal secretion known as venom were endowed by nature. Snake venom is a very poisonous mixture consisting of a number of molecules such as carbohydrates, nucleosides, amino acids, lipids, proteins and peptides, making it a cocktail of diversified molecules. Snake envenomation is responsible for the disruption in the envenomed victim’s fundamental physiological processes contributing to serious health problems. Millions of snakebites are recorded annually, and due to snake venom poisoning, a significant number of individuals are injured and die. However, through technical developments, many fatal snake venom toxins have found potential applications as diagnostic agents, medicinal agents, or drug leads. From the development of Captopril, the first drug derived from Bothrops jarararaca’s bradykinin potentiating peptide, to the disintegrins that have potent activity against some forms of cancers. Therefore, components of snake venom have shown tremendous potential for the development of lead compounds for new drugs. Complementary tools and techniques are currently being used to isolate and characterize peptides and to study their potential uses as molecular probes and templates for drug development and design investigation models.

Cardiovascular Effects of Snake Toxins: Cardiotoxicity and Cardioprotection.

Snake venoms, as complex mixtures of peptides and proteins, affect various vital systems of the organism. One of the main targets of the toxic components from snake venoms is the cardiovascular system. Venom proteins and peptides can act in different ways, exhibiting either cardiotoxic or cardioprotective effects. The principal classes of these compounds are cobra cardiotoxins, phospholipases A2, and natriuretic, as well as bradykinin-potentiating peptides. There is another group of proteins capable of enhancing angiogenesis, which include, e.g., vascular endothelial growth factors possessing hypotensive and cardioprotective activities. Venom proteins and peptides exhibiting cardiotropic and vasoactive effects are promising candidates for the design of new drugs capable of preventing or constricting the development of pathological processes in cardiovascular diseases, which are currently the leading cause of death worldwide. For example, a bradykinin-potentiating peptide from Bothrops jararaca snake venom was the first snake venom compound used to create the widely used antihypertensive drugs captopril and enalapril. In this paper, we review the current state of research on snake venom components affecting the cardiovascular system and analyse the mechanisms of physiological action of these toxins and the prospects for their medical application.

Quantity - but not diversity - of secreted peptides and proteins increases with age in the tree frog Pithecopus nordestinus.

Background:Amphibians inhabit the terrestrial environment, a conquest achieved after several evolutionary steps, which were still insufficient to make them completely independent of the aquatic environment. These processes gave rise to many morphological and physiological changes, making their skin (and cutaneous secretion) rich in bioactive molecules. Among the tree frogs, the secretion is composed mainly of peptides; but alkaloids, proteins and steroids can also be found depending on the species. The most known class of biologically active molecules is the antimicrobial peptides (AMPs) that act against bacteria, fungi and protozoans. Although these molecules are well-studied among the hylids, AMPs ontogeny remains unknown. Therefore, we performed peptidomic and proteomic analyses of Pithecopus nordestinus (formerly Phyllomedusa nordestina) in order to evaluate the peptide content in post-metamorphosed juveniles and adult individuals.Methods: Cutaneous secretion of both life stages of individuals was obtained and analyzed by LC-MS/MS after reduction and alkylation of disulfide bonds or reduction, alkylation and hydrolysis by trypsin.Results: Differences in the TIC profile of juveniles and adults in both treatments were observed. Moreover, the proteomic data revealed known proteins and peptides, with slight differences in the composition, according to the life stage and the treatment. AMPs were identified, and bradykinin-potentiating peptides were observed in trypsin-treated samples, which suggests a protein source of such peptide (cryptide).Conclusion: In general, skin secretion contents were similar between juveniles and adults, varying in quantity, indicating that the different stages of life are reflected in the number of molecules and not on their diversity.

Novel Bradykinin-Potentiating Peptides and Three-Finger Toxins from Viper Venom: Combined NGS Venom Gland Transcriptomics and Quantitative Venom Proteomics of the Azemiops feae Viper.

Feae’s viper Azemipos feae belongs to the Azemiopinae subfamily of the Viperidae family. The effects of Viperidae venoms are mostly coagulopathic with limited neurotoxicity manifested by phospholipases A2. From A. feae venom, we have earlier isolated azemiopsin, a novel neurotoxin inhibiting the nicotinic acetylcholine receptor. To characterize other A. feae toxins, we applied label-free quantitative proteomics, which revealed 120 unique proteins, the most abundant being serine proteinases and phospholipases A2. In total, toxins representing 14 families were identified, among which bradykinin-potentiating peptides with unique amino acid sequences possessed biological activity in vivo. The proteomic analysis revealed also basal (commonly known as non-conventional) three-finger toxins belonging to the group of those possessing neurotoxic activity. This is the first indication of the presence of three-finger neurotoxins in viper venom. In parallel, the transcriptomic analysis of venom gland performed by Illumina next-generation sequencing further revealed 206 putative venom transcripts. Together, the study unveiled the venom proteome and venom gland transciptome of A. feae, which in general resemble those of other snakes from the Viperidae family. However, new toxins not found earlier in viper venom and including three-finger toxins and unusual bradykinin-potentiating peptides were discovered.

Fast venomic analysis of Crotalus durissus terrificus from northeastern Argentina.

The complete knowledge of the toxins that make up venoms is the base for the treatment of snake accidents victims and the selection of specimens for the preparation of venom pools for antivenom production. In this work, we used a fast and direct venomics approach to identify the toxin families in the C.d. terrificus venom, a Southern American Neotropical rattlesnake. The RP-HPLC separation profile of pooled venom from adult specimens followed by mass spectrometry analysis revealed that C.d. terrificus’ venom proteome is composed of 12 protein families, which are unevenly distributed in the venom, e.g., there are few major proteins in the venom's composition phospholipase A2, serine proteinase, crotamine and L-amino acid oxidase. At the same time, the proteome analysis revealed a small set of proteins with low quantity (less than 1.5%), both enzymes (metaloprotease, phospholipase B and 5′-nucleotidase) and proteins (Bradykinin potentiating and C-type natriuretic peptides, C-type lectin convulxin and nerve growth factor). To sum up, this research is the first venomic report of C.d.terrificus venom from Argentina. This proved to be crotamine positive venom that has a lower metalloprotease content than C.d. terrificus venoms from other regions. This information could be used in the discovery of future pharmacological agents or targets in antivenom therapy.

Venomics and biochemical analysis of the black-tailed horned pitviper, Mixcoatlus melanurus, and characterization of Melanurutoxin, a novel crotoxin homolog

We report a structural and functional venomics characterization of the black-tailed horned pitviper, Mixcoatlus melanurus. The venom phenotype of this small and elusive pitviper endemic to México comprise peptides and proteins of 16 toxin families whose relative abundance mirror those of neurotoxic (type II) venoms described for some species within genera distributed in Central Asia (Gloydius) and the Americas (Sistrurus, Crotalus, Ophryacus, and Bothriechis). A novel β-neurotoxic heterodimeric PLA2, termed Melanurutoxin was characterized. With a relative abundance of 14.8% of the total M. melanurus venom proteome and a median lethal dose of 0.31 μg/g mouse body weight, Melanurutoxin accounted for 37.8% of the lethality of the whole venom (0.82 μg/g). The low percentage (1.1%) of snake venom metalloproteinases (PIII-SVMPs) and the high content of Melanurutoxin and bradykinin-potentiating peptides (BPP, 16%) found in the type-II venom proteome of M. melanurus correlate with the severe hypotension and neurotoxicity leading to neuromuscular blockade, flaccid paralysis and respiratory arrest observed in ex vivo neuromuscular junction experiments and in vivo experimental murine envenoming. Mexican antivenoms manufactured by Birmex and Bioclon showed low neutralization potency per vial (95 LD50s, Birmex; 114 LD50s, Antivipmyn®), and failed to reverse completely the paralysis and the hypotensive effect induced by the black-tailed horned pitviper, Mixcoatlus melanurus. We suggest that the impaired ability of these antivenoms to neutralize the neurotoxicity of M. melanurus venom may be attributed to the use of immunization mixtures that include venom of taxa, C. basiliscus (Birmex) and C. simus (Antivipmyn®), that contain only small amounts of Melanurutoxin-like β-neurotoxic heterodimeric PLA2s. Biological significanceThis study represents the first proteomics and funcional investigations conducted on the venom of the black-tailed horned, Mixcoatlus melanurus, a pitviper species endemic to México. The venom's features unveiled through combination of bottom-up venomics and ex vivo and in vivo functional assays provided complementary evidence pointing to severe hypotension and neurotoxicity leading to neuromuscular blockade, flaccid paralysis and respiratory arrest as the predominant mechanism of murine prey immobilization and death caused by M. melanurus. A novel β-neurotoxic heterodimeric PLA2, coined Melanurutoxin, was identified as a major contributor to the lethality of the whole venom. Our study also showed the inefficacy of two commercial Mexican antivenoms to reverse competely the paralytic and hypotensive effects induced by M. melanurus venom in the murine model. We hypothesize that the impaired ability of these antivenoms to neutralize the neurotoxicity of M. melanurus venom should be ascribed to the use as immunogens of venoms that contain only small amounts of Melanurutoxin-like β-neurotoxic heterodimeric PLA2s.

Proteomic and toxinological characterization of Peruvian pitviper Bothrops brazili (“jergón shushupe”), venom

Bothrops brazili is a pitviper from Amazonian region, responsible for many accidents in Peru. Despite its relevance, its venom has not been extensively characterized. In the present work, Bothrops brazili venom (BbV) components were analyzed by RP-HPLC, SDS-PAGE and MALDI-TOF/TOF. Approximately 37 proteins were identified, belonging to 7 families. Snake venom metalloproteinases (SVMPs) were the most abundant proteins of the venom (33.05%), followed by snake venom serine proteinases (SVSPs, 26.11%), phospholipases A2 (PLA2, 25.57%), snake C-type lectins (CTLs, 9.61%), L-aminoacid oxidase (LAAO, 3.80%), cystein-rich secretory proteins (CRISP, 1.67%) and Bradykinin-potentiating peptide (BPP, 0.20%). In vitro enzymatic activities of BbV showed high levels of SVMP activity and reduced Hyal activity in comparison with other bothropic venoms. Furthermore, BbV reduced VERO cells viability. ELISA and Western Blotting showed that both Peruvian and Brazilian bothropic antivenoms were able to recognize BbV components. This work provides an overview of BbV venom content and indicates a potential efficiency of Peruvian and Brazilian antivenoms to treat accidents with this species.

How ACE inhibitors transformed the renin–angiotensin system

The renin-angiotensin system (RAS) now underlies the successful treatment of almost 50% of the patients in cardiovascular medicine, with serious possibilities of extension to diabetes, Alzheimer's disease and cancer. This clinical transformation started just over 50 years ago, with the unexpected identification of a bradykinin-potentiating peptide from snake venom, as a potent inhibitor of ACE which led to the development of the first synthetic inhibitor, captopril, followed by the angiotensin receptor blockers. This article analyses the transformation of the RAS into its different stages, from academic experiments to clinical use and back to the laboratory, identifying the critical events involved, both clinical and scientific. The analysis also assesses the contributions of chance, coincidence, and conviction that were crucial in this transformation. Although questions remain, the transformation of the RAS over the past five decades provides a success story for medicine, for pharmacology, and, most significantly, for patients.

Correlation of Venom Toxinome Composition of Indian Red Scorpion (Mesobuthus tamulus) with Clinical Manifestations of Scorpion Stings: Failure of Commercial Antivenom to Immune-Recognize the Abundance of Low Molecular Mass Toxins of This Venom.

The Indian red scorpion (Mesobuthus tamulus), with its life-threatening sting, is the world's most dangerous species of scorpion. The toxinome composition of M. tamulus venom was determined by tandem mass spectrometry (MS) analysis of venom protein bands separated by SDS-PAGE. A total of 110 venom toxins were identified from searching the MS data against the Buthidae family (taxid: 6855) of toxin entries in nonredundant protein databases. The Na+ and K+ ion channel toxins taken together are the most abundant toxins (76.7%) giving rise to the neurotoxic nature of this venom. The other minor toxin classes in the M. tamulus venom proteome are serine protease-like protein (2.9%), serine protease inhibitor (2.2%), antimicrobial peptide (2.3%), hyaluronidase (2.2%), makatoxin (2.1%), lipolysis potentiating peptides (1.2%), neurotoxin affecting Cl- channel (1%), parabutoporin (0.6%), Ca2+ channel toxins (0.8%), bradykinin potentiating peptides (0.2%), HMG CoA reductase inhibitor (0.1%), and other toxins with unknown pharmacological activity (7.7%). Several of these toxins have been shown to be promising drug candidates. M. tamulus venom does not show enzymatic activity (phospholipase A2, l-amino acid oxidase, adenosine tri-, di-, and monophosphatase, hyaluronidase, metalloproteinase, and fibrinogenolytic), in vitro hemolytic activity, interference with blood coagulation, or platelet modulation properties. The clinical manifestations post M. tamulus sting have been described in the literature and are well correlated with its venom proteome composition. An abundance of low molecular mass toxins (3-15 kDa) are responsible for exerting the major pharmacological effects of M. tamulus venom, though they are poorly immune-recognized by commercial scorpion antivenom. This is a major concern for the development of effective antivenom therapy against scorpion stings.