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Factor VIIa and the extracellular domains of human tissue factor form a compact complex: A study by X‐ray and neutron solution scattering
Author(s) -
Ashton Alun W.,
Kemball-Cook Geoffrey,
Johnson Daniel J.D.,
Martin David M.A.,
O'Brien Donogh P.,
Tuddenham Edward G.D.,
Perkins Stephen J.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01093-t
Subject(s) - x ray , factor viia , extracellular , factor (programming language) , chemistry , neutron scattering , small angle x ray scattering , form factor (electronics) , scattering , tissue factor , biophysics , materials science , physics , optics , biology , biochemistry , medicine , computer science , coagulation , quantum mechanics , programming language
The four‐domain structure of human factor VIIa and the two‐domain structure of tissue factor form a tight complex to initiate blood coagulation. By solution scattering, the mean X‐ray and neutron radii of gyration R G (which determine macromolecular elongation) were found to be 3.25 nm, 2.13 nm and 3.14 nm (± 0.13 nm) for factor VIIa, the extracellular region of tissue factor and their complex in that order. The mean cross‐sectional radii of gyration R XS were 1.33 nm, 0.56 nm and 1.42 nm (± 0.13 nm) in that order. The mean lengths were 10.3 nm, 7.7 nm and 10.2 nm in that order. The data show that, in solution, the free proteins have extended domain structures, and the complex is formed by a compact side‐by‐side alignment of the two proteins along their long axes. The high binding affinity of tissue factor for factor VIIa may thus be accounted for by the occurrence of many intermolecular contacts in the complex.