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Updated: Jan 2, 2026
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Crystallization and Structural Determination of an Enzyme:Substrate Complex by Serial Crystallography in a Versatile Microfluidic Chip
Published on: March 20, 2021
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Crystal structures of uninhibited factor VIIa link its cofactor and substrate-assisted activation to specific
Katrin Sichler1, David W Banner, Allan D'Arcy
1Max-Planck-Institut für Biochemie, D-82152, Martinsried, Germany.
Journal of Molecular Biology
|September 13, 2002
Summary
Recombinant factor VIIa was produced and crystallized, revealing how ethylene glycol binding stabilizes its structure. This provides insights into the activation mechanisms of factor VIIa and factor IXa in coagulation.
Area of Science:
- Biochemistry
- Structural Biology
- Hematology
Background:
- Factor VIIa is crucial for hemostasis and thrombosis, initiating the extrinsic coagulation cascade.
- Its activation mechanism is complex and a key pharmaceutical research target.
- Understanding factor VIIa structure-function relationships is vital for drug development.
Purpose of the Study:
- To achieve recombinant production of N-terminally truncated factor VII (rf7) and its activated form (rf7a).
- To elucidate the structural basis of factor VIIa activation and regulation.
- To investigate the role of ethylene glycol in factor VIIa activity modulation.
Main Methods:
- Recombinant expression of truncated factor VII in E. coli.
- In vitro oxidative folding requiring ethylene glycol.
- Crystallization of activated recombinant factor VIIa (rf7a) with benzamidine.
- X-ray crystallography at 1.69Å resolution.
- Comparison with inhibitor-free crystal forms.
Main Results:
- Successful production of rf7 and crystallization of rf7a.
- Identified structural features of factor VIIa stimulation, mimicking cofactor (tissue factor) and substrate (factor X) binding.
- Discovered a bell-shaped activity modulation by ethylene glycol, specific to factor VIIa and factor IXa.
- Localized the ethylene glycol-binding site to the 60 loop, inducing conformational changes.
Conclusions:
- Benzamidine and sulfate ions can stabilize factor VIIa structure, mimicking activation.
- Ethylene glycol binding significantly alters the 60 loop, impacting substrate recognition.
- These findings offer a mechanistic framework for substrate-assisted catalysis in factor VIIa and factor IXa.
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