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Open AccessArticle

Binding of Hanatoxin to the Voltage Sensor of Kv2.1

by Rong Chen, Anna Robinson and Shin-Ho Chung

Toxins 2012, 4(12), 1552-1564; https://doi.org/10.3390/toxins4121552 - 18 Dec 2012

Cited by 11 | Viewed by 7557

Abstract

Hanatoxin 1 (HaTx1) is a polypeptide toxin isolated from spider venoms. HaTx1 inhibits the voltage-gated potassium channel kv2.1 potently with nanomolar affinities. Its receptor site has been shown to contain the S3b-S4a paddle of the voltage sensor (VS). Here, the binding of HaTx1 [...] Read more.

Hanatoxin 1 (HaTx1) is a polypeptide toxin isolated from spider venoms. HaTx1 inhibits the voltage-gated potassium channel kv2.1 potently with nanomolar affinities. Its receptor site has been shown to contain the S3b-S4a paddle of the voltage sensor (VS). Here, the binding of HaTx1 to the VSs of human Kv2.1 in the open and resting states are examined using a molecular docking method and molecular dynamics. Molecular docking calculations predict two distinct binding modes for the VS in the resting state. In the two binding modes, the toxin binds the S3b-S4a from S2 and S3 helices, or from S1 and S4 helices. Both modes are found to be stable when embedded in a lipid bilayer. Only the mode in which the toxin binds the S3b-S4a paddle from S2 and S3 helices is consistent with mutagenesis experiments, and considered to be correct. The toxin is then docked to the VS in the open state, and the toxin-VS interactions are found to be less favorable. Computational mutagenesis calculations performed on F278R and E281K mutant VSs show that the mutations may reduce toxin binding affinity by weakening the non-bonded interactions between the toxin and the VS. Overall, our calculations reproduce a wide range of experimental data, and suggest that HaTx1 binds to the S3b-S4a paddle of Kv2.1 from S2 and S3 helices. Full article

(This article belongs to the Special Issue Animal Venoms)

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133 KiB

Open AccessArticle

Asp Viper (Vipera aspis) Envenomation: Experience of the Marseille Poison Centre from 1996 to 2008

by Luc De Haro, Mathieu Glaizal, Lucia Tichadou, Ingrid Blanc-Brisset and Maryvonne Hayek-Lanthois

Toxins 2009, 1(2), 100-112; https://doi.org/10.3390/toxins1020100 - 24 Nov 2009

Cited by 55 | Viewed by 12149

Abstract

A retrospective case review study of viper envenomations collected by the Marseille’s Poison Centre between 1996 and 2008 was performed. Results: 174 cases were studied (52 grade 1 = G1, 90 G2 and 32 G3). G1 patients received symptomatic treatments (average hospital stay [...] Read more.

A retrospective case review study of viper envenomations collected by the Marseille’s Poison Centre between 1996 and 2008 was performed. Results: 174 cases were studied (52 grade 1 = G1, 90 G2 and 32 G3). G1 patients received symptomatic treatments (average hospital stay 0.96 day). One hundred and six (106) of the G2/G3 patients were treated with the antivenom Viperfav* (2.1+/-0.9 days in hospital), while 15 of them received symptomatic treatments only (plus one immediate death) (8.1+/-4 days in hospital, 2 of them died). The hospital stay was significantly reduced in the antivenom treated group (p < 0.001), and none of the 106 antivenom treated patients had immediate (anaphylaxis) or delayed (serum sickness) allergic reactions. Conclusion: Viperfav* antivenom was safe and effective for treating asp viper venom-induced toxicity. Full article

(This article belongs to the Special Issue Animal Venoms)

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Review

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285 KiB

Open AccessReview

Fibrolase: Trials and Tribulations

by Francis S. Markland and Steve Swenson

Toxins 2010, 2(4), 793-808; https://doi.org/10.3390/toxins2040793 - 20 Apr 2010

Cited by 21 | Viewed by 10144

Abstract

Fibrolase is the fibrinolytic enzyme isolated from Agkistrodon contortrix contortrix (southern copperhead snake) venom. The enzyme was purified by a three-step HPLC procedure and was shown to be homogeneous by standard criteria including reverse phase HPLC, molecular sieve chromatography and SDS-PAGE. The purified [...] Read more.

Fibrolase is the fibrinolytic enzyme isolated from Agkistrodon contortrix contortrix (southern copperhead snake) venom. The enzyme was purified by a three-step HPLC procedure and was shown to be homogeneous by standard criteria including reverse phase HPLC, molecular sieve chromatography and SDS-PAGE. The purified enzyme is a zinc metalloproteinase containing one mole of zinc. It is composed of 203 amino acids with a blocked amino-terminus due to cyclization of the terminal Gln residue. Fibrolase shares a significant degree of homology with enzymes of the reprolysin sub-family of metalloproteinases including an active site homology of close to 100%; it is rapidly inhibited by chelating agents such as EDTA, and by alpha2-macroglobulin (α2M). The enzyme is a direct-acting thrombolytic agent and does not rely on plasminogen for clot dissolution. Fibrolase rapidly cleaves the A(α)-chain of fibrinogen and the B(β)-chain at a slower rate; it has no activity on the γ-chain. The enzyme exhibits the same specificity with fibrin, cleaving the α-chain more rapidly than the β-chain. Fibrolase was shown to have very effective thrombolytic activity in a reoccluding carotid arterial thrombosis model in the canine. A recombinant version of the enzyme was made in yeast by Amgen, Inc. (Thousand Oaks, CA, USA) and called alfimeprase. Alfimeprase is identical to fibrolase except for a two amino acid truncation at the amino-terminus and the insertion of a new amino-terminal amino acid in the truncated protein; these changes lead to a more stable enzyme for prolonged storage. Alfimeprase was taken into clinical trials by Nuvelo, Inc. (San Carlos, CA), which licensed the enzyme from Amgen. Alfimeprase was successful in Phase I and II clinical trials for peripheral arterial occlusion (PAO) and central venous access device (CVAD) occlusion. However, in Phase III trials alfimeprase did not meet the expected end points in either PAO or CVAD occlusion and in a Phaase II stroke trial, and Nuvelo dropped further development in 2008. Full article

(This article belongs to the Special Issue Animal Venoms)

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Open AccessReview

Venom Proteins of the Parasitoid Wasp Nasonia vitripennis: Recent Discovery of an Untapped Pharmacopee

by Ellen L. Danneels, David B. Rivers and Dirk C. De Graaf

Toxins 2010, 2(4), 494-516; https://doi.org/10.3390/toxins2040494 - 30 Mar 2010

Cited by 92 | Viewed by 16070

Abstract

Adult females of Nasonia vitripennis inject a venomous mixture into its host flies prior to oviposition. Recently, the entire genome of this ectoparasitoid wasp was sequenced, enabling the identification of 79 venom proteins. The next challenge will be to unravel their specific functions, [...] Read more.

Adult females of Nasonia vitripennis inject a venomous mixture into its host flies prior to oviposition. Recently, the entire genome of this ectoparasitoid wasp was sequenced, enabling the identification of 79 venom proteins. The next challenge will be to unravel their specific functions, but based on homolog studies, some predictions already can be made. Parasitization has an enormous impact on hosts physiology of which five major effects are discussed in this review: the impact on immune responses, induction of developmental arrest, increases in lipid levels, apoptosis and nutrient releases. The value of deciphering this venom is also discussed. Full article

(This article belongs to the Special Issue Animal Venoms)

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144 KiB

Open AccessReview

Inhibition of Hemorragic Snake Venom Components: Old and New Approaches

by Isabella Panfoli, Daniela Calzia, Silvia Ravera and Alessandro Morelli

Toxins 2010, 2(4), 417-427; https://doi.org/10.3390/toxins2040417 - 25 Mar 2010

Cited by 35 | Viewed by 11453

Abstract

Snake venoms are complex toxin mixtures. Viperidae and Crotalidae venoms, which are hemotoxic, are responsible for most of the envenomations around the world. Administration of antivenins aimed at the neutralization of toxins in humans is prone to potential risks. Neutralization of snake venom [...] Read more.

Snake venoms are complex toxin mixtures. Viperidae and Crotalidae venoms, which are hemotoxic, are responsible for most of the envenomations around the world. Administration of antivenins aimed at the neutralization of toxins in humans is prone to potential risks. Neutralization of snake venom toxins has been achieved through different approaches: plant extracts have been utilized in etnomedicine. Direct electric current from low voltage showed neutralizing properties against venom phospholipase A2 and metalloproteases. This mini-review summarizes new achievements in venom key component inhibition. A deeper knowledge of alternative ways to inhibit venom toxins may provide supplemental treatments to serum therapy. Full article

(This article belongs to the Special Issue Animal Venoms)

648 KiB

Open AccessReview

Animal Toxins: How is Complexity Represented in Databases?

by Florence Jungo, Anne Estreicher, Amos Bairoch, Lydie Bougueleret and Ioannis Xenarios

Toxins 2010, 2(2), 262-282; https://doi.org/10.3390/toxins2020261 - 21 Feb 2010

Cited by 14 | Viewed by 13291

Abstract

Peptide toxins synthesized by venomous animals have been extensively studied in the last decades. To be useful to the scientific community, this knowledge has been stored, annotated and made easy to retrieve by several databases. The aim of this article is to present [...] Read more.

Peptide toxins synthesized by venomous animals have been extensively studied in the last decades. To be useful to the scientific community, this knowledge has been stored, annotated and made easy to retrieve by several databases. The aim of this article is to present what type of information users can access from each database. ArachnoServer and ConoServer focus on spider toxins and cone snail toxins, respectively. UniProtKB, a generalist protein knowledgebase, has an animal toxin-dedicated annotation program that includes toxins from all venomous animals. Finally, the ATDB metadatabase compiles data and annotations from other databases and provides toxin ontology. Full article

(This article belongs to the Special Issue Animal Venoms)

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370 KiB

Open AccessReview

Bothrops lanceolatus Bites: Guidelines for Severity Assessment and Emergent Management

by Dabor Resiere, Bruno Mégarbane, Ruddy Valentino, Hossein Mehdaoui and Laurent Thomas

Toxins 2010, 2(1), 163-173; https://doi.org/10.3390/toxins2010163 - 22 Jan 2010

Cited by 40 | Viewed by 15355

Abstract

Approximately 20–30 declared snakebite cases occurin Martinique each year. Bothrops lanceolatus, a member of the Crotalidae family, is considered to be the only involved snake. B. lanceolatus, commonly named “Fer-de-Lance”, is endemic and only found on this Caribbean island. Envenomation local [...] Read more.

Approximately 20–30 declared snakebite cases occurin Martinique each year. Bothrops lanceolatus, a member of the Crotalidae family, is considered to be the only involved snake. B. lanceolatus, commonly named “Fer-de-Lance”, is endemic and only found on this Caribbean island. Envenomation local features include the presence of fang marks, swelling, pain, bleeding from punctures, and ecchymosis. Severe envenomation is associated with multiple systemic thromboses appearing within 48 h of the bite and resulting in cerebral, myocardial or pulmonary infarctions. Diagnosis requires first of all identification of the snake. Coagulation tests are helpful to identify thrombocytopenia or disseminated intravascular coagulation. A clinical score based on 4 grades is helpful to assess envonimation severity. A specific monovalent equine anti-venom (Bothrofav^®, Sanofi-Pasteur, France) to neutralize B. lanceolatus venom is available. Its early administration within 6h from the biting in case of progressive local injures, general signs or coagulation disturbances is effective to prevent severe thrombosis and coagulopathy. Its tolerance is considered to be good. Despite an increasing incidence of bites, no deaths have been recently attributed to B. lanceolatus in Martinique, probably due to the currently recommended strategy of early antivenom administration when required. Full article

(This article belongs to the Special Issue Animal Venoms)

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2695 KiB

Open AccessReview

Structure and Function of Snake Venom Proteins Affecting Platelet Plug Formation

by Taei Matsui, Jiharu Hamako and Koiti Titani

Toxins 2010, 2(1), 10-23; https://doi.org/10.3390/toxins2010010 - 28 Dec 2009

Cited by 16 | Viewed by 15000

Abstract

Many snake venom proteins have been isolated that affect platelet plug formation by interacting either with platelet integrins, membrane glycoprotein Ib (GPIb), or plasma von Willebrand factor (VWF). Among them, disintegrins purified from various snake venoms are strong inhibitors of platelet aggregation. Botrocetin [...] Read more.

Many snake venom proteins have been isolated that affect platelet plug formation by interacting either with platelet integrins, membrane glycoprotein Ib (GPIb), or plasma von Willebrand factor (VWF). Among them, disintegrins purified from various snake venoms are strong inhibitors of platelet aggregation. Botrocetin and bitiscetin derived from Bothrops jararaca and Bitis arietans venom, respectively, induce VWF-dependent platelet agglutination in vitro. Several GPIb-binding proteins have also been isolated from snake venoms. In this review, we focus on the structure and function of those snake venom proteins that influence platelet plug formation. These proteins are potentially useful as reagents for the sub-diagnosis of platelet disorder or von Willebrand disease, as well as for clinical and basic research of thrombosis and hemostasis. Full article

(This article belongs to the Special Issue Animal Venoms)

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