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Characterization of recombinant human coagulation factor XFriuli
D J Kim1, A Girolami, H L James
1Department of Biochemistry, University of Texas Health Center at Tyler 75710, USA.
Thrombosis and Haemostasis
|February 1, 1996
Summary
Naturally occurring plasma factor XFriuli (pFXFr), a variant of coagulation factor X, exhibits impaired activation and catalytic function due to a specific mutation. This molecular defect explains the moderate bleeding tendency observed in individuals with this factor X variant.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Naturally occurring plasma factor XFriuli (pFXFr) shows reduced activation and catalytic potential.
- A specific mutation, Ser for Pro at position 343, is suspected to cause these functional defects.
Purpose of the Study:
- To confirm that the Ser343Pro substitution in factor XFriuli causes multi-functional defects.
- To investigate the molecular basis of the impaired procoagulant activity.
Main Methods:
- Site-directed mutagenesis was used to create recombinant factor XFriuli (rFXFr).
- rFXFr was purified from human embryonic kidney cells (293).
- Molecular modeling was employed to analyze structural changes.
Main Results:
- Recombinant factor XFriuli (rFXFr) exhibited normal molecular size and processing.
- Post-translational modification content (Gla and beta-OH-Asp) was comparable to normal factor X.
- rFXFr showed the same impaired activation and catalytic specific activities as pFXFr.
- Molecular modeling indicated a new hydrogen bond involving Ser-343, potentially disrupting substrate binding.
Conclusions:
- The Ser343Pro mutation in factor XFriuli is confirmed as the cause of its dysfunctional activation and catalytic potentials.
- This molecular defect accounts for the moderate bleeding tendency in individuals with the factor XFriuli variant.