1kli

From Proteopedia

Revision as of 14:14, 15 February 2008

Cofactor-and substrate-assisted activation of factor VIIa

Overview

Factor VIIa initiates the extrinsic coagulation cascade; this event, requires a delicately balanced regulation that is implemented on different, levels, including a sophisticated multi-step activation mechanism of, factor VII. Its central role in hemostasis and thrombosis makes factor, VIIa a key target of pharmaceutical research. We succeeded, for the first, time, in recombinantly producing N-terminally truncated factor VII (rf7), in an Escherichia coli expression system by employing an oxidative, in, vitro, folding protocol, which depends critically on the presence of, ethylene glycol. Activated recombinant factor VIIa (rf7a) was crystallised, in the presence of the reversible S1-site inhibitor benzamidine., Comparison of this 1.69A crystal structure with that of an inhibitor-free, and sulphate-free, but isomorphous crystal form identified structural, details of factor VIIa stimulation. The stabilisation of Asp189-Ser190 by, benzamidine and the capping of the intermediate helix by a sulphate ion, appear to be sufficient to mimic the disorder-order transition conferred, by the cofactor tissue factor (TF) and the substrate factor X. Factor VIIa, shares with the homologous factor IXa, but not factor Xa, a bell-shaped, activity modulation dependent on ethylene glycol. The ethylene, glycol-binding site of rf7a was identified in the vicinity of the 60 loop., Ethylene glycol binding induces a significant conformational rearrangement, of the 60 loop. This region serves as a recognition site of the, physiologic substrate, factor X, which is common to both factor VIIa and, factor IXa. These results provide a mechanistic framework of, substrate-assisted catalysis of both factor VIIa and factor IXa.

Disease

Known diseases associated with this structure: Factor VII deficiency OMIM:[227500], Myocardial infarction, decreased susceptibility to OMIM:[227500]

About this Structure

1KLI is a Protein complex structure of sequences from Homo sapiens with , , and as ligands. Active as Coagulation factor VIIa, with EC number 3.4.21.21 Full crystallographic information is available from OCA.

Reference

Crystal structures of uninhibited factor VIIa link its cofactor and substrate-assisted activation to specific interactions., Sichler K, Banner DW, D'Arcy A, Hopfner KP, Huber R, Bode W, Kresse GB, Kopetzki E, Brandstetter H, J Mol Biol. 2002 Sep 20;322(3):591-603. PMID:12225752

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