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Updated: Jul 31, 2026
05:48
Rapid Generation of Amyloid from Native Proteins In vitro
Published on: December 6, 2013
Inhibitory action of amyloid precursor protein against human Hageman factor (factor XII)
H Niwano1, P B Embury, B D Greenberg
1Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH.
The Journal of Laboratory and Clinical Medicine
|February 1, 1995
Summary
Amyloid precursor proteins, independent of their Kunitz protease inhibitor domain, can regulate hemostasis by inhibiting Hageman factor activation. This suggests a broader role in blood clotting beyond protease inhibition.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Amyloid precursor protein (APP) isoforms containing Kunitz protease inhibitor domains are released by blood cells and inhibit proteases like trypsin and thrombin.
- The role of APP in hemostasis, particularly its interaction with the intrinsic coagulation pathway, requires further investigation.
Purpose of the Study:
- To investigate the effects of recombinant APP isoforms (BAC770 and BAC695) on activated Hageman factor (factor XII), activated factor X (Stuart factor), and thrombin.
- To determine if APP's influence on hemostasis is dependent on its Kunitz protease inhibitor domain.
Main Methods:
- Production of recombinant APP isoforms (BAC770 and BAC695) using Baculovirus expression in insect cells.
- Assays to measure inhibition of alpha-thrombin, activated factor X, and Hageman factor activation.
- Partial thromboplastin time (PTT) measurements.
- Investigation of APP interaction with ellagic acid and bismuth subgallate in Hageman factor activation.
- Assessment of heparin's effect on APP-mediated inhibition.
Main Results:
- Neither BAC695 nor BAC770 inhibited human alpha-thrombin or activated factor X.
- Both APP isoforms prolonged partial thromboplastin time; BAC770 contains the Kunitz domain, BAC695 does not.
- Both APP forms inhibited ellagic acid-induced Hageman factor activation but not activated Hageman factor itself.
- Heparin enhanced the inhibition of Hageman factor activation by both APP forms, suggesting a non-Kunitz heparin-binding domain.
Conclusions:
- Amyloid precursor proteins regulate hemostasis through mechanisms not solely dependent on the Kunitz protease inhibitor domain.
- A heparin-binding domain, likely not within the Kunitz domain, may mediate APP's inhibition of Hageman factor activation by negatively charged agents.
- APP isoforms play a significant role in controlling hemostasis, with implications for understanding blood coagulation.
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