E. Persson et al., Rational design of coagulation factor VIIa variants with substantially increased intrinsic activity, P NAS US, 98(24), 2001, pp. 13583-13588
Citations number
29
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
A trace amount of coagulation factor VII (FVII) circulates in the blood in
the activated form, FVIIa(EC 3.4.21.21), formed by internal proteolysis. To
avoid disseminated thrombus formation, FVIIa remains in a conformation wit
h zymogen-like properties. Association with tissue factor (TF), locally exp
osed upon vascular injury, is necessary to render FVIIa biologically active
and initiate blood clotting. We have designed potent mutants of FVIIa by r
eplacing residues believed to function as determinants for the inherent zym
ogenicity. The TF-independent rate of factor X activation was dramatically
improved, up to about 100-fold faster than that obtained with the wild-type
enzyme and close to that of the FVIIa-soluble TF complex. The mutants appe
ar to retain the substrate specificity of the parent enzyme and can be furt
her stimulated by TF. Insights into the mechanism behind the increased acti
vity of the mutants, presumably also pertinent to the TF-induced, allosteri
c stimulation of FVIIa activity, were obtained by studying their calcium de
pendence and the accessibility of the N terminus of the protease domain to
chemical modification. The FVIIa analogues promise to offer a more efficaci
ous treatment of bleeding episodes especially in hemophiliacs with inhibito
ry antibodies precluding conventional replacement therapy.