Purification and characterization of platelet aggregation inhibitors from snake venoms

Department of Biochemistry and Molecular Biology, University of Southern California, School of Medicine, Los Angeles 90033.
Thrombosis Research (Impact Factor: 2.43). 02/1994; 73(1):39-52. DOI: 10.1016/0049-3848(94)90052-3
Source: PubMed

ABSTRACT Proteins that inhibit glycoprotein (GP) IIb/IIIa mediated platelet aggregation have been purified from the venom of two snake species. A small platelet aggregation inhibitor (p1.AI), multisquamatin (Mr = 5,700), was purified from Echis multisquamatus venom by hydrophobic interaction HPLC and two steps on C18 reverse phase HPLC. A larger p1.AI, contortrostatin (Mr = 15,000), was purified by a similar HPLC procedure from the venom of Agkistrodon contortrix contortrix. Both p1.AIs inhibit ADP-induced human, canine and rabbit platelet aggregation using platelet rich plasma (PRP). Multisquamatin has an IC50 of 97 nM, 281 nM and 333 nM for human, canine and rabbit PRP, respectively. Contortrostatin has an IC50 of 49 nM, 120 nM and 1,150 nM for human, canine and rabbit PRP, respectively. In a competitive binding assay using 125I-7E3 (a monoclonal antibody to GPIIb/IIIa that inhibits platelet aggregation) both contortrostatin and multisquamatin demonstrated GPIIb/IIIa specific binding to human and canine platelets. The IC50 for contortrostatin displacement of 7E3 binding to human and canine GPIIb-/IIIa is 27 nM and 16 nM, respectively and for multisquamatin it is 3 nM and 63 nM, respectively. Our results indicate that both p1.AIs inhibit platelet aggregation by binding with high affinity to GPIIb/IIIa.

Download full-text


Available from: Francis S Markland, Jul 30, 2015
  • Source
    • "Venom of Agkistrodon contortrix contortrix was purchased from Miami Serpentarium (Punta Gorda, FL) and CN was purified as previously described (Trikha et al., 1994b). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Vicrostatin (VCN) is a chimeric recombinant disintegrin generated in Origami B (DE3) Escherichia coli as a genetic fusion between the C-terminal tail of a viperid disintegrin echistatin and crotalid disintegrin contortrostatin (CN). The therapeutic modulation of multiple integrin pathways via soluble disintegrins was previously shown by us and others to elicit potent anti-angiogenic and anti-metastatic effects in several animal cancer models. Despite these favorable attributes, these polypeptides are notoriously difficult to produce recombinantly in significant quantity due to their structure which requires the correct pairing of multiple disulfide bonds for biological activity. In this report, we show that VCN can be reliably produced in large amounts (yields in excess of 200 mg of active purified disintegrin per liter of bacterial culture) in Origami B (DE3), an E. coli expression strain engineered to support the folding of disulfide-rich heterologous proteins directly in its oxidative cytoplasmic compartment. VCN retains the integrin binding specificity of both parental molecules it was derived from, but with a different binding affinity profile. While competing for the same integrin receptors that are preferentially upregulated in the tumor microenvironment, VCN exerts a potent inhibitory effect on endothelial cell (EC) migration and tube formation in a dose-dependent manner, by forcing these cells to undergo significant actin cytoskeleton reorganization when exposed to this agent in vitro. Moreover, VCN has a direct effect on breast cancer cells inhibiting their in vitro motility. In an effort to address our main goal of developing a clinically relevant delivery method for recombinant disintegrins, VCN was efficiently packaged in liposomes (LVCN) and evaluated in vivo in an animal breast cancer model. Our data demonstrate that LVCN is well tolerated, its intravenous administration inducing a significant delay in tumor growth and an increase in animal survival, results that can be partially explained by potent tumor apoptotic effects.
    Toxicon 02/2011; 59(4):472-86. DOI:10.1016/j.toxicon.2011.02.020 · 2.58 Impact Factor
  • Source
    • "Interestingly, in contrast with a single chain Arg-Gly-Asp containing disintegrin, multisquamatin, contortrostatin was shown capable of activating intracellular signaling pathways giving rise to tyrosine phosphorylation [62]. Using animal models of cancer contortrostatin has been demonstrated to block experimental metastasis of melanoma and limit breast cancer progression [63]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Poisons and the toxins found in venomous and poisonous organisms have been the focus of much research over the past 70 years, most of which has been directed at understanding the biochemical and physiological mechanisms by which they elicit their dramatic pathological consequences. Much knowledge has been gained in terms of how poisons and venoms and their composite toxins give rise to the syndromes associated with envenoming and poisoning and in some isolated cases there have been a few such agents promoted for therapeutic use. However, it has only been in the past decade that an explosion of interest has occurred in mining these natural, highly evolved libraries of bioactive toxins and poisons for use in pharmacotherapeutics as drugs or drug leads as well as in diagnostic applications. We ascribe this recent phenomenon to advances in toxinology which have provided investigators with a relatively thorough understanding of the nature of venoms and their biologically active toxins: particularly with regard to the peptidomes and proteomes of venoms. This is in conjunction with our greatly improved understanding of the etiology of many human diseases and the identification of sites of potential therapeutic intervention. In this review we provide an overview of some of the toxins, toxin derivatives or poisons from animal venoms and secretions which are in various stages of development for use as pharmaceuticals or diagnostics in human diseases. As one will recognize, developments in this field suggest that toxinology is now entering a golden age in terms of the identification and use of toxins as potent novel pharmaceuticals.
    Current pharmaceutical design 02/2007; 13(28):2927-34. DOI:10.2174/138161207782023739 · 3.29 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Disintegrins are Arg-Gly-Asp-containing proteins that inhibit integrin-mediated cell-cell and cell-matrix interactions. We have purified a disintegrin, contortrostatin, from Agkistrodon contortrix contortrix snake venom that is a potent inhibitor of human metastatic melanoma (M24 met) cell adhesion to extracellular matrix proteins. Contortrostatin inhibits M24 met cell adhesion to type I collagen, vitronectin, and fibronectin with 50% inhibitory concentration values of 20, 75, and 220 nM, respectively. Contortrostatin does not significantly inhibit adhesion of M24 met cells to laminin. 125I-labeled contortrostatin binds to M24 met cells in a saturable and displaceable manner. Scatchard analysis indicates that there are two binding sites for 125I-labeled contortrostatin on the surface of these cells. High affinity binding has a Kd of 3 nM with 165,000 sites/cells low affinity binding has a Kd of 60 nM with 500,000 sites/cell. Immobilized contortrostatin can support adhesion of M24 met cells; this binding is blocked by a monoclonal antibody to the beta 1 integrin subunit and by an antibody to the fibronectin receptor alpha 5 beta 1. The anti-vitronectin receptor (alpha v beta 5) monoclonal antibody which blocks adhesion of M24 met cells to immobilized vitronectin does not block binding of M24 met cells to immobilized contortrostatin. In an in vivo experimental metastasis model system, contortrostatin at 20 micrograms and 100 micrograms inhibits lung colonization of M24 met cells (5 x 10(5)), injected in the tail vein of scid mice, by 51 and 73%, respectively. We conclude that contortrostatin is a potent inhibitor of beta 1 integrin-mediated M24 met cell adhesion in vitro and that it also inhibits lung colonization in vivo.
    Cancer Research 10/1994; 54(18):4993-8. · 9.28 Impact Factor
Show more