Taipan Venom Research Articles

The effect of several viper venoms on prothrombin Padua.

The effect of four viper venoms (Oxyuranus scutellatus, Notechis scutatus scutatus, Echis carinatus, Naja nigricollis) on prothrombin Padua has been studied. Using Oxyuranus scutellatus venom and Notechis scutatus scutatus venom, prothrombin activity resulted to be moderately decreased similarly to what observed with other one-stage and two-stage methods. On the contrary, using Echis carinatus venom a normal level was obtained. No clotting was observed using the Naja nigricollis venom, regardless of the concentration used. The normal level of factor II obtained with Echis carinatus venom as compared with the low levels obtained with the other venoms, suggests that it acts on a different site of the prothrombin molecule.

Isolation and characterization of multiple forms of human thrombin

Established procedures for the isolation of human prothrombin (1) and thrombin (2) have been modified so that large quantities of human thrombin could be isolated in a rapid, yet facile, manner. Thrombins derived from the activation of human prothrombin with thromboplastin or venom from the Australian Taipan (Oxyuranus Scutellatus Scutellatus) have been isolated and characterized with respect to their molecular weights and isoelectric points. Multiple active human thrombin components were found. Molecular weights of proteins found in these preparations conformed to the molecular weights reported for bovine thrombins. Activity studies with the synthetic substrate Benzoyl-Phe-Val-Arg-p-nitro-anilide and inhibitors fibrinopeptides A and B, have been performed. The majority of coagulant and esterase activity of the human thrombin preparations was associated with a protein component with an isoelectric point of 7,1. Coagulant, but no esterase activity, was found at isoelectric point 6, 7. Additional minor peaks of both activities had isoelectric points of 5,6 and 6,2, which are the sole isoelectric points reported previously for bovine thrombin. Results of the characterization studies show that thromboplastin and taipan venom activation produce very similar thrombins.

Self-Damping Mechanism in Blood Coagulation

Two reactions of the extrinsic pathway of coagulation, the activations of Factor X and prothrombin, have been studied in purified systems and shown to be self-damping. Factor X was activated by the tissue factor-Factor VII complex, and prothrombin by two systems: the coagulant protein of Taipan venom, and the physiological complex of activated Factor X, Factor V, lipid, and calcium ions. In each case the yield of enzyme, activated Factor X or thrombin, is a function of the concentration of activator. These and other observations are considered as a basis for a control mechanism in coagulation.

Activation of prothrombin with (taipan snake) venom

Complete activation of prothrombin with taipan snake () venom yields thrombin and two fragments, fragment-1 and fragment-2, which by the criteria of ion-exchange chromatography and SDS gel electrophoresis are indistinguishable from the products of Xa-catalyzed prothrombin activation. Activation in the presence of diisopropylfluorophosphate with either taipan venom or Xa results in the formation of thrombin-sensitive fragment 1·2, a single polypeptide composed of fragments-1 and 2. Whereas the rate of venom-catalyzed activation is enhanced 20–30 times by phospholipid vesicles, Factor V is without effect in either the presence or absence of phospholipid. The venom activity is not inhibited by diisopropylfluorophosphate, phenylmethylsulfonylfluoride, soybean trypsin inhibitor, p-hydroxymercuribenzoate or iodoacetate. The venom does not hydrolyze N2-toluene-p-sulfonyl-L-arginine methyl ester, N2-benzoyl-L-arginine ethyl ester or N-acetyl-L-tyrosine ethyl ester. The rate of venom-catalyzed prothrombin activation is not affected by plasma factor Xa inhibitor plus heparin.