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Correlation of factor IXa subsite modulations with effects on substrate discrimination
P F Neuenschwander1, K J Deadmond, K Zepeda
1Center for Biomedical Research, The University of Texas Health Science Center at Tyler, Tyler, TX 75708, USA. pierre.neuenschwander@uthct.edu
Journal of Thrombosis and Haemostasis : JTH
|January 4, 2012
Summary
Small molecules like ethylene glycol, Ca(2+), and low molecular weight heparin (LMWH) alter factor IXa (FIXa) active sites. These changes affect FIXa substrate discrimination and function, offering insights for drug design.
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Factor IXa (FIXa) transforms from a latent to a potent procoagulant form.
- Small molecules like ethylene glycol, Ca(2+), and low molecular weight heparin (LMWH) partially affect FIXa function.
- Understanding FIXa allosteric regulation is crucial for its coagulant activity.
Purpose of the Study:
- To correlate structural changes induced by modulators with FIXa substrate discrimination and function.
- To investigate the impact of ethylene glycol, Ca(2+), and LMWH on FIXa activity.
- To elucidate the mechanisms of FIXa regulation.
Main Methods:
- Utilized a peptidomics-based mass spectrometry (MS) approach.
- Examined hydrolysis patterns of pentapeptide libraries by FIXa.
- Studied FIXa under various conditions in a soluble, active enzyme system.
Main Results:
- Ethylene glycol altered the S3 subsite, increasing tolerance to P3 side chains.
- Ca(2+) enhanced tolerance at the S2 subsite.
- LMWH altered both S2 and S1' subsites, impacting FIXa substrate recognition.
Conclusions:
- Demonstrated the role of plasticity in regulating FIXa function and substrate discrimination.
- Provided crucial insights into active site modulations by physiologic cofactors.
- Highlighted potential applications in future drug design for modulating FIXa activity.
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