Lengths of the C-Terminus and Interconnecting Loops Impact Stability of Spider-Derived Gating Modifier Toxins

A phage-displayed disulfide constrained peptide discovery platform yields novel human plasma protein binders

Disulfide constrained peptides (DCPs) show great potential as templates for drug discovery. They are characterized by conserved cysteine residues that form intramolecular disulfide bonds. Taking advantage of phage display technology, we designed and generated twenty-six DCP phage libraries with enriched molecular diversity to enable the discovery of ligands against disease-causing proteins of interest. The libraries were designed based on five DCP scaffolds, namely Momordica charantia 1 (Mch1), gurmarin, Asteropsin-A, antimicrobial peptide-1 (AMP-1), and potato carboxypeptidase inhibitor (CPI). We also report optimized workflows for screening and producing synthetic and recombinant DCPs. Examples of novel DCP binders identified against various protein targets are presented, including human IgG Fc, serum albumin, vascular endothelial growth factor-A (VEGF-A) and platelet-derived growth factor (PDGF). We identified DCPs against human IgG Fc and serum albumin with sub-micromolar affinity from primary panning campaigns, providing alternative tools for potential half-life extension of peptides and small protein therapeutics. Overall, the molecular diversity of the DCP scaffolds included in the designed libraries, coupled with their distinct biochemical and biophysical properties, enables efficient and robust identification of de novo binders to drug targets of therapeutic relevance.

Structural Conformation and Activity of Spider-Derived Inhibitory Cystine Knot Peptide Pn3a Are Modulated by pH

Numerous spider venom-derived gating modifier toxins exhibit conformational heterogeneity during purification by reversed-phase high-performance liquid chromatography (RP-HPLC). This conformational exchange is especially peculiar for peptides containing an inhibitor cystine knot motif, which confers excellent structural stability under conditions that are not conducive to disulfide shuffling. This phenomenon is often attributed to proline cis/trans isomerization but has also been observed in peptides that do not contain a proline residue. Pn3a is one such peptide forming two chromatographically distinguishable peaks that readily interconvert following the purification of either conformer. The nature of this exchange was previously uncharacterized due to the fast rate of conversion in solution, making isolation of the conformers impossible. In the present study, an N-terminal modification of Pn3a enabled the isolation of the individual conformers, allowing activity assays to be conducted on the individual conformers using electrophysiology. The conformers were analyzed separately by nuclear magnetic resonance spectroscopy (NMR) to study their structural differences. RP-HPLC and NMR were used to study the mechanism of exchange. The later-eluting conformer was the active conformer with a rigid structure that corresponds to the published structure of Pn3a, while NMR analysis revealed the earlier-eluting conformer to be inactive and disordered. The exchange was found to be pH-dependent, arising in acidic solutions, possibly due to reversible disruption and formation of intramolecular salt bridges. This study reveals the nature of non-proline conformational exchange observed in Pn3a and possibly other disulfide-rich peptides, highlighting that the structure and activity of some disulfide-stabilized peptides can be dramatically susceptible to disruption.

NaV1.7 Channel Blocker [Ala5, Phe6, Leu26, Arg28]GpTx-1 Attenuates CFA-induced Inflammatory Hypersensitivity in Rats via Endogenous Enkephalin Mechanism

Venom-derived Na_V1.7 channel blockers have promising prospects in pain management. The 34-residue tarantula peptide GpTx-1 is a potent Na_V1.7 channel blocker. Its powerful analog [Ala⁵, Phe⁶, Leu²⁶, Arg²⁸]GpTx-1 (GpTx-1-71) displayed excellent Na_V1.7 selectivity and analgesic properties in mice. The current study aimed to elucidate the anti-hyperalgesic activities of GpTx-1-71 in inflammatory pain and reveal the underlying mechanisms. Our results demonstrated that intrathecal and intraplantar injections of GpTx-1-71 dose-dependently attenuated CFA-induced inflammatory hypersensitivity in rats. Moreover, GpTx-1-71-induced anti-hyperalgesia was significantly reduced by opioid receptor antagonists and the enkephalin antibody and diminished in proenkephalin (Penk) gene knockout animals. Consistently, GpTx-1-71 treatment increased the enkephalin level in the spinal dorsal horn and promoted the Penk transcription and enkephalin release in primary dorsal root ganglion (DRG) neurons, wherein sodium played a crucial role in these processes. Mass spectrometry analysis revealed that GpTx-1-71 mainly promoted the secretion of Met-enkephalin but not Leu-enkephalin from DRG neurons. In addition, the combination of subtherapeutic Met-enkephalin and GpTx-1-71 produced synergistic anti-hyperalgesia in CFA-induced inflammatory hypersensitivity. These findings suggest that the endogenous enkephalin pathway is essential for GpTx-1-71-induced spinal and peripheral analgesia in inflammatory pain. PERSPECTIVE: This article presents a possible pharmacological mechanism underlying Na_V1.7 blocker-induced analgesia in inflammatory pain, which helps us to better understand and develop venom-based painkillers for incurable pain.

Evaluation of Efficient Non-reducing Enzymatic and Chemical Ligation Strategies for Complex Disulfide-Rich Peptides

Double-knotted peptides identified in venoms and synthetic bivalent peptide constructs targeting ion channels are emerging tools for the study of ion channel pharmacology and physiology. These highly complex and disulfide-rich peptides contain two individual cystine knots, each comprising six cysteines and three disulfide bonds. Until now, native double-knotted peptides, such as Hi1a and DkTx, have only been isolated from venom or produced recombinantly, whereas engineered double-knotted peptides have successfully been produced through enzymatic ligation using sortase A to form a seamless amide bond at the ligation site between two knotted toxins, and by alkyne/azide click chemistry, joining two peptide knots via a triazole linkage. To further pursue these double-knotted peptides as pharmacological tools or probes for therapeutically relevant ion channels, we sought to identify a robust methodology resulting in a high yield product that lends itself to rapid production and facile mutational studies. In this study, we evaluated the ligation efficiency of enzymatic (sortase A5°, butelase 1, wild-type OaAEP 1, C247A-OaAEP 1, and peptiligase) and mild chemical approaches (α-ketoacid-hydroxylamine, KAHA) for forming a native amide bond linking the toxins while maintaining the native disulfide connectivity of each pre-folded peptide. We used two NaV1.7 inhibitors: PaurTx3, a spider-derived gating modifier peptide, and KIIIA, a small cone snail-derived pore blocker peptide, which have previously been shown to increase affinity and inhibitory potency on hNaV1.7 when ligated together. Correctly folded peptides were successfully ligated in varying yields, without disulfide bond shuffling or reduction, with sortase A5° being the most efficient, resulting in 60% ligation conversion within 15 min. In addition, electrophysiology studies demonstrated that for these two peptides, the amino acid composition of the linker did not affect the activity of the double-knotted peptides. This study demonstrates the powerful application of enzymes in efficiently ligating complex disulfide-rich peptides, paving the way for facile production of double-knotted peptides.

Purification and characterization of peptides Ap2, Ap3 and Ap5 (ω-toxins) from the venom of the Brazilian tarantula Acanthoscurria paulensis

Peptides isolated from spider venoms are of pharmacological interest due to their neurotoxic activity, acting on voltage-dependent ion channels present in different types of human body tissues. Three peptide toxins titled as Ap2, Ap3 and Ap5 were purified by RP-HPLC from Acanthoscurria paulensis venom. They were partially sequenced by MALDI In-source Decay method and their sequences were completed and confirmed by transcriptome analysis of the venom gland. The Ap2, Ap3 and Ap5 peptides have, respectively, 42, 41 and 46 amino acid residues, and experimental molecular masses of 4886.3, 4883.7 and 5454.7 Da, with the Ap2 peptide presenting an amidated C-terminus. Amongst the assayed channels - NaV1.1, NaV1.5, NaV1.7, CaV1.2, CaV2.1 and CaV2.2 - Ap2, Ap3 and Ap5 inhibited 20-30 % of CaV2.1 current at 1 μM concentration. Ap3 also inhibited sodium current in NaV1.1, Nav1.5 and Nav1.7 channels by 6.6 ± 1.91 % (p = 0.0276), 4.2 ± 1.09 % (p = 0.0185) and 16.05 ± 2.75 % (p = 0.0282), respectively. Considering that Ap2, Ap3 and Ap5 belong to the 'U'-unknown family of spider toxins, which has few descriptions of biological activity, the present work contributes to the knowledge of these peptides and demonstrates this potential as channel modulators.

Pharmacological Inhibition of the Voltage-Gated Sodium Channel NaV1.7 Alleviates Chronic Visceral Pain in a Rodent Model of Irritable Bowel Syndrome

The human nociceptor-specific voltage-gated sodium channel 1.7 (hNa_V1.7) is critical for sensing various types of somatic pain, but it appears not to play a primary role in acute visceral pain. However, its role in chronic visceral pain remains to be determined. We used assay-guided fractionation to isolate a novel hNa_V1.7 inhibitor, Tsp1a, from tarantula venom. Tsp1a is 28-residue peptide that potently inhibits hNa_V1.7 (IC₅₀ = 10 nM), with greater than 100-fold selectivity over hNa_V1.3-hNa_V1.6, 45-fold selectivity over hNa_V1.1, and 24-fold selectivity over hNa_V1.2. Tsp1a is a gating modifier that inhibits Na_V1.7 by inducing a hyperpolarizing shift in the voltage-dependence of channel inactivation and slowing recovery from fast inactivation. NMR studies revealed that Tsp1a adopts a classical knottin fold, and like many knottin peptides, it is exceptionally stable in human serum. Remarkably, intracolonic administration of Tsp1a completely reversed chronic visceral hypersensitivity in a mouse model of irritable bowel syndrome. The ability of Tsp1a to reduce visceral hypersensitivity in a model of irritable bowel syndrome suggests that pharmacological inhibition of hNa_V1.7 at peripheral sensory nerve endings might be a viable approach for eliciting analgesia in patients suffering from chronic visceral pain.

Recent developments in animal venom peptide nanotherapeutics with improved selectivity for cancer cells

Animal venoms are a rich source of bioactive peptides that efficiently modulate key receptors and ion channels involved in cellular excitability to rapidly neutralize their prey or predators. As such, they have been a wellspring of highly useful pharmacological tools for decades. Besides targeting ion channels, some venom peptides exhibit strong cytotoxic activity and preferentially affect cancer over healthy cells. This is unlikely to be driven by an evolutionary impetus, and differences in tumor cells and the tumor microenvironment are probably behind the serendipitous selectivity shown by some venom peptides. However, strategies such as bioconjugation and nanotechnologies are showing potential to improve their selectivity and potency, thereby paving the way to efficiently harness new anticancer mechanisms offered by venom peptides. This review aims to highlight advances in nano- and chemotherapeutic tools and prospective anti-cancer drug leads derived from animal venom peptides.

A spider-venom peptide with multitarget activity on sodium and calcium channels alleviates chronic visceral pain in a model of irritable bowel syndrome

ABSTRACT

Chronic pain is a serious debilitating condition that affects ∼20% of the world's population. Currently available drugs fail to produce effective pain relief in many patients and have dose-limiting side effects. Several voltage-gated sodium (NaV) and calcium (CaV) channels are implicated in the etiology of chronic pain, particularly NaV1.1, NaV1.3, NaV1.7-NaV1.9, CaV2.2, and CaV3.2. Numerous NaV and CaV modulators have been described, but with few exceptions, they display poor potency and/or selectivity for pain-related channel subtypes. Here, we report the discovery and characterization of 2 novel tarantula-venom peptides (Tap1a and Tap2a) isolated from Theraphosa apophysis venom that modulate the activity of both NaV and CaV3 channels. Tap1a and Tap2a inhibited on-target NaV and CaV3 channels at nanomolar to micromolar concentrations and displayed moderate off-target selectivity for NaV1.6 and weak affinity for NaV1.4 and NaV1.5. The most potent inhibitor, Tap1a, nearly ablated neuronal mechanosensitivity in afferent fibers innervating the colon and the bladder, with in vivo intracolonic administration reversing colonic mechanical hypersensitivity in a mouse model of irritable bowel syndrome. These findings suggest that targeting a specific combination of NaV and CaV3 subtypes provides a novel route for treatment of chronic visceral pain.

Enzymatic Ligation of Disulfide-Rich Animal Venom Peptides: Using Sortase A to Form Double-Knotted Peptides

Sortase A is a thiol transpeptidase expressed by Gram-positive bacteria. This enzyme is capable of site-specifically ligating peptides containing the C-terminal recognition motif LPXTG to peptides containing an N-terminal polyglycine sequence, forming a native peptide bond. Here, we describe the preparation and application of sortase A to the ligation of two individually folded disulfide-rich animal venom peptides in order to form a heterodimeric double-knotted peptide with a native peptide linker. This method is mild enough to preserve the structures and disulfide connectivities of the peptides during ligation. We employed a highly efficient sortase A pentamutant (SrtA5°), which brings the reaction to completion within 15 min with a ~50-80% yield of ligated peptide.

Recombinant PaurTx-3, a spider toxin, inhibits sodium channels and decreases membrane excitability in DRG neurons

Voltage-gated sodium channels are critical for the generation and propagation of action potentials. Gating modifier toxins from spider venom can modulate the gating mechanism of sodium channels and thus have potential as drug leads. Here, we established expression of the gating modifier toxin PaurTx-3, a sodium channel inhibitor found in the venom of the spider Phrixotrichus auratus. Whole-cell voltage-clamp recordings indicated that recombinant PaurTx-3 (rPaurTx-3) inhibited Nav1.4, Nav1.5, and Nav1.7 currents with IC₅₀ values of 61 nM, 72 nM, and 25 nM, respectively. Furthermore, rPaurTx-3 irreversibly inhibited Nav1.7 currents, but had 60-70% recovery in Nav1.4 and Nav1.5 after washing with a bath solution. rPaurTx-3 also hyperpolarized the voltage-dependent steady-state inactivation curve and significantly slowed recovery from fast inactivation of Nav1.7. Current-clamp recordings showed that rPaurTx-3 suppressed small DRG neuron activity. The biological activity assay findings for rPaurTx-3 support its potent pharmacological effect in Nav1.7 and small DRG neurons.

Two Novel Peptide Toxins from the Spider Cyriopagopus longipes Inhibit Tetrodotoxin-Sensitive Sodium Channels

Sodium channels play a critical role in the generation and propagation of action potentials in excitable tissues, such as nerves, cardiac muscle, and skeletal muscle, and are the primary targets of toxins found in animal venoms. Here, two novel peptide toxins (Cl6a and Cl6b) were isolated from the venom of the spider Cyriopagopus longipes and characterized. Cl6a and Cl6b were shown to be inhibitors of tetrodotoxin-sensitive (TTX-S), but not TTX-resistant, sodium channels. Among the TTX-S channels investigated, Cl6a and Cl6b showed the highest degree of inhibition against NaV1.7 (half-maximal inhibitory concentration (IC₅₀) of 11.0 ± 2.5 nM and 18.8 ± 2.4 nM, respectively) in an irreversible manner that does not alter channel activation, inactivation, or repriming kinetics. Moreover, analysis of NaV1.7/NaV1.8 chimeric channels revealed that Cl6b is a site 4 neurotoxin. Site-directed mutagenesis analysis indicated that D816, V817, and E818 observably affected the efficacy of the Cl6b-NaV1.7 interaction, suggesting that these residues might directly affect the interaction of NaV1.7 with Cl6b. Taken together, these two novel peptide toxins act as potent and sustained NaV1.7 blockers and may have potential in the pharmacological study of sodium channels.

Manipulation of a spider peptide toxin alters its affinity for lipid bilayers and potency and selectivity for voltage-gated sodium channel subtype 1.7

Huwentoxin-IV (HwTx-IV) is a gating modifier peptide toxin from spiders that has weak affinity for the lipid bilayer. As some gating modifier toxins have affinity for model lipid bilayers, a tripartite relationship among gating modifier toxins, voltage-gated ion channels, and the lipid membrane surrounding the channels has been proposed. We previously designed an HwTx-IV analogue (gHwTx-IV) with reduced negative charge and increased hydrophobic surface profile, which displays increased lipid bilayer affinity and in vitro activity at the voltage-gated sodium channel subtype 1.7 (NaV1.7), a channel targeted in pain management. Here, we show that replacements of the positively-charged residues that contribute to the activity of the peptide can improve gHwTx-IV's potency and selectivity for NaV1.7. Using HwTx-IV, gHwTx-IV, [R26A]gHwTx-IV, [K27A]gHwTx-IV, and [R29A]gHwTx-IV variants, we examined their potency and selectivity at human NaV1.7 and their affinity for the lipid bilayer. [R26A]gHwTx-IV consistently displayed the most improved potency and selectivity for NaV1.7, examined alongside off-target NaVs, compared with HwTx-IV and gHwTx-IV. The lipid affinity of each of the three novel analogues was weaker than that of gHwTx-IV, but stronger than that of HwTx-IV, suggesting a possible relationship between in vitro potency at NaV1.7 and affinity for lipid bilayers. In a murine NaV1.7 engagement model, [R26A]gHwTx-IV exhibited an efficacy comparable with that of native HwTx-IV. In summary, this study reports the development of an HwTx-IV analogue with improved in vitro selectivity for the pain target NaV1.7 and with an in vivo efficacy similar to that of native HwTx-IV.

Weaponisation 'on the fly': Convergent recruitment of knottin and defensin peptide scaffolds into the venom of predatory assassin flies

Many arthropod venom peptides have potential as bioinsecticides, drug leads, and pharmacological tools due to their specific neuromodulatory functions. Assassin flies (Asilidae) are a family of predaceous dipterans that produce a unique and complex peptide-rich venom for killing insect prey and deterring predators. However, very little is known about the structure and function of their venom peptides. We therefore used an E. coli periplasmic expression system to express four disulfide-rich peptides that we previously reported to exist in venom of the giant assassin fly Dolopus genitalis. After purification, each recombinant peptide eluted from a C18 column at a position closely matching its natural counterpart, strongly suggesting adoption of the native tertiary fold. Injection of purified recombinant peptides into blowflies (Lucilia cuprina) and crickets (Acheta domestica) revealed that two of the four recombinant peptides, named rDg3b and rDg12, inhibited escape behaviour in a manner that was rapid in onset (<1 min) and reversible. Homonuclear NMR solution structures revealed that rDg3b and rDg12 adopt cystine-stabilised α/ß defensin and inhibitor cystine knot folds, respectively. Although the closest known homologues of rDg3b at the level of primary structure are dipteran antimicrobial peptides such as sapecin and lucifensin, a DALI search showed that the tertiary structure of rDg3b most closely resembles the K_V11.1-specific α-potassium channel toxin CnErg1 from venom of the scorpion Centruroides noxius. This is mainly due to the deletion of a large, unstructured loop between the first and second cysteine residues present in Dg3b homologues from non-asiloid, but not existing in asiloid, species. Patch-clamp electrophysiology experiments revealed that rDg3b shifts the voltage-dependence of K_V11.1 channel activation to more depolarised potentials, but has no effect on K_V1.3, K_V2.1, K_V10.1, K_Ca1.1, or the Drosophila Shaker channel. Although rDg12 shares the inhibitor cystine knot structure of many gating modifier toxins, rDg12 did not affect any of these K_V channel subtypes. Our results demonstrate that multiple disulfide-rich peptide scaffolds have been convergently recruited into asilid and other animal venoms, and they provide insight into the molecular evolution accompanying their weaponisation.

Spider Knottin Pharmacology at Voltage-Gated Sodium Channels and Their Potential to Modulate Pain Pathways

Voltage-gated sodium channels (Na_Vs) are a key determinant of neuronal signalling. Neurotoxins from diverse taxa that selectively activate or inhibit Na_V channels have helped unravel the role of Na_V channels in diseases, including chronic pain. Spider venoms contain the most diverse array of inhibitor cystine knot (ICK) toxins (knottins). This review provides an overview on how spider knottins modulate Na_V channels and describes the structural features and molecular determinants that influence their affinity and subtype selectivity. Genetic and functional evidence support a major involvement of Na_V subtypes in various chronic pain conditions. The exquisite inhibitory properties of spider knottins over key Na_V subtypes make them the best lead molecules for the development of novel analgesics to treat chronic pain.

From identification to functional characterization of cyriotoxin-1a, an antinociceptive toxin from the spider Cyriopagopus schioedtei

BACKGROUND AND PURPOSE

The Na_V 1.7 channel is highly expressed in dorsal root ganglia of the sensory nervous system and plays a central role in the pain signalling process. We investigated a library prepared from original venoms of 117 different animals to identify new selective inhibitors of this target.

EXPERIMENTAL APPROACH

We used high throughput screening of a large venom collection using automated patch-clamp experiments on human voltage-gated sodium channel subtypes and then in vitro and in vivo electrophysiological experiments to characterize the active peptides that have been purified, sequenced, and chemically synthesized. Analgesic effects were evaluated in vivo in mice models.

KEY RESULTS

We identified cyriotoxin-1a (CyrTx-1a), a novel peptide isolated from Cyriopagopus schioedtei spider venom, as a candidate for further characterization. This 33 amino acids toxin belongs to the inhibitor cystine knot structural family and inhibits hNa_V 1.1-1.3 and 1.6-1.7 channels in the low nanomolar range, compared to the micromolar range for hNa_V 1.4-1.5 and 1.8 channels. CyrTx-1a was 920 times more efficient at inhibiting tetrodotoxin (TTX)-sensitive than TTX-resistant sodium currents recorded from adult mouse dorsal root ganglia neurons and in vivo electrophysiological experiments showed that CyrTx-1a was approximately 170 times less efficient than huwentoxin-IV at altering mouse skeletal neuromuscular excitability properties. CyrTx-1a exhibited an analgesic effect in mice by increasing reaction time in the hot-plate assay.

CONCLUSIONS AND IMPLICATIONS

The pharmacological profile of CyrTx-1a paves the way for further molecular engineering aimed to optimize the potential antinociceptive properties of this peptide.

Peptide-Membrane Interactions Affect the Inhibitory Potency and Selectivity of Spider Toxins ProTx-II and GpTx-1

Gating modifier toxins (GMTs) from spider venom can inhibit voltage gated sodium channels (Na_Vs) involved in pain signal transmission, including the Na_V1.7 subtype. GMTs have a conserved amphipathic structure that allow them to interact with membranes and also with charged residues in regions of Na_V that are exposed at the cell surface. ProTx-II and GpTx-1 are GMTs able to inhibit Na_V1.7 with high potency, but they differ in their ability to bind to membranes and in their selectivity over other Na_V subtypes. To explore these differences and gain detailed information on their membrane-binding ability and how this relates to potency and selectivity, we examined previously described Na_V1.7 potent/selective GpTx-1 analogues and new ProTx-II analogues designed to reduce membrane binding and improve selectivity for Na_V1.7. Our studies reveal that the number and type of hydrophobic residues as well as how they are presented at the surface determine the affinity of ProTx-II and GpTx-1 for membranes and that altering these residues can have dramatic effects on Na_V inhibitory activity. We demonstrate that strong peptide-membrane interactions are not essential for inhibiting Na_V1.7 and propose that hydrophobic interactions instead play an important role in positioning the GMT at the membrane surface proximal to exposed Na_V residues, thereby affecting peptide-channel interactions. Our detailed structure-activity relationship study highlights the challenges of designing GMT-based molecules that simultaneously achieve high potency and selectivity for Na_V1.7, as single mutations can induce local changes in GMT structure that can have a major impact on Na_V-inhibitory activity.

Gating modifier toxins isolated from spider venom: Modulation of voltage-gated sodium channels and the role of lipid membranes

Gating modifier toxins (GMTs) are venom-derived peptides isolated from spiders and other venomous creatures and modulate activity of disease-relevant voltage-gated ion channels and are therefore being pursued as therapeutic leads. The amphipathic surface profile of GMTs has prompted the proposal that some GMTs simultaneously bind to the cell membrane and voltage-gated ion channels in a trimolecular complex. Here, we examined whether there is a relationship among spider GMT amphipathicity, membrane binding, and potency or selectivity for voltage-gated sodium (Na_V) channels. We used NMR spectroscopy and in silico calculations to examine the structures and physicochemical properties of a panel of nine GMTs and deployed surface plasmon resonance to measure GMT affinity for lipids putatively found in proximity to Na_V channels. Electrophysiology was used to quantify GMT activity on Na_V1.7, an ion channel linked to chronic pain. Selectivity of the peptides was further examined against a panel of Na_V channel subtypes. We show that GMTs adsorb to the outer leaflet of anionic lipid bilayers through electrostatic interactions. We did not observe a direct correlation between GMT amphipathicity and affinity for lipid bilayers. Furthermore, GMT-lipid bilayer interactions did not correlate with potency or selectivity for Na_Vs. We therefore propose that increased membrane binding is unlikely to improve subtype selectivity and that the conserved amphipathic GMT surface profile is an adaptation that facilitates simultaneous modulation of multiple Na_Vs.

Toxins in Drug Discovery and Pharmacology

Venoms from marine and terrestrial animals (cone snails, scorpions, spiders, snakes, centipedes, cnidarian, etc.) can be seen as an untapped cocktail of biologically active compounds, being increasingly recognized as a new emerging source of peptide-based therapeutics.