Showing papers by "James A. Huntington published in 2014"
TL;DR: In this article, a crystal structure of a competent fragment of Kgp encompassing the catalytic cysteine peptidase domain and a downstream immunoglobulin superfamily-like domain was reported.
70 citations
TL;DR: This review examines how the special features of thrombin have been exploited by evolution to achieve inhibition of the ultimate coagulation protease.
Abstract: The serine protease thrombin is the effector enzyme of blood coagulation. It has many activities critical for the formation of stable clots, including cleavage of fibrinogen to fibrin, activation of platelets and conversion of procofactors to active cofactors. Thrombin carries-out its multiple functions by utilising three special features: a deep active site cleft and two anion binding exosites (exosite I and II). Similarly, thrombin inhibitors have evolved to exploit the unique features of thrombin to achieve rapid and specific inactivation of thrombin. Exogenous thrombin inhibitors come from several different protein families and are generally found in the saliva of haematophagous animals (blood suckers) as part of an anticoagulant cocktail that allows them to feed. Crystal structures of several of these inhibitors reveal how peptides and proteins can be targeted to thrombin in different and interesting ways. Thrombin activity must also be regulated by endogenous inhibitors so that thrombi do not occlude blood flow and cause thrombosis. A single protein family, the serpins, provides all four of the endogenous thrombin inhibitors found in man. The crystal structures of these serpins bound to thrombin have been solved, revealing a similar exosite-dependence on complex formation. In addition to forming the recognition complex, serpins destroy the structure of thrombin, allowing them to be released from cofactors and substrates for clearance. This review examines how the special features of thrombin have been exploited by evolution to achieve inhibition of the ultimate coagulation protease.
50 citations
TL;DR: It is predicted that as a consequence of the truncation, the variant TM is shed from the endothelial surface into the blood plasma, which would promote systemic protein C activation and early cessation of thrombin generation within a developing hemostatic clot, thereby explaining the phenotype of posttraumatic bleeding observed within this family.
40 citations
TL;DR: The results indicate that the peptide corresponding to the C-terminal portion of GpIbα and the entire extracellular domain bind exclusively to thrombin's exosite II, which serves to recruitThrombin activity to the platelet surface while leaving exosite I free for PAR-1 recognition.
34 citations
TL;DR: Small-angle x-ray scattering was used to characterize Z- α1AT polymers in solution and showed that the Z-α1AT trimer, tetramer, and pentamer all form ring-like structures in strong support of a common domain-swap polymerization mechanism that can lead to self-terminating polymers.
13 citations
TL;DR: The crystal structure of Pseutarin C is used as a starting point for homology modelling and assembly of the full human prothrombinase complex and provides a powerful resource for contextualizing previous data and for designing future experiments.
Abstract: Thrombin is generated from prothrombin through cleavage at two sites by the prothrombinase complex. Prothrombinase is composed of a protease, factor (f) Xa, and a cofactor, fVa, which interact on negatively charged phospholipid surfaces and cleave prothrombin into thrombin 300 000 times faster than fXa alone. The balance between bleeding and thrombosis depends on the amount of thrombin produced, and this in turn depends on the function of the prothrombinase complex. How fXa and fVa interact and how improved prothrombin processing is conferred are of critical importance for understanding healthy and pathological blood clotting. Until recently, little structural information was available, and molecular models were built on partial structures with assembly guided by biochemical data. Last year our group published a crystal structure of a prothrombinase complex from the venom of the Australian Eastern Brown snake (known as Pseutarin C). Here we use the crystal structure of Pseutarin C as a starting point for homology modelling and assembly of the full human prothrombinase complex. The interface is complementary in shape and charge, and is consistent with much of the published biochemical data. The model of human prothrombinase presented here provides a powerful resource for contextualizing previous data and for designing future experiments.
13 citations
TL;DR: The structure of the catalytic and immunoglobulin-type domains of Kgp has been solved in complex with a covalent inhibitor, revealing the working mechanism and may lead to the design of drugs to selectively treat periodontitis.
11 citations
Patent•
15 Dec 2014
TL;DR: In this paper, a modification of the P4, P2, P1 and/or P1' residues within the reactive center loop (RCL) was proposed to improve the specificity of anticoagulant proteases.
Abstract: This invention relates pro-coagulant serpin molecules engineered by modification of the P4, P2, P1 and/or P1' residues within the reactive center loop (RCL) to display increased specificity for anticoagulant proteases These modified serpin molecules may be useful in therapy, for example as pro-coagulants for the treatment of bleeding
3 citations