Related Experiment Videos
Structure-function relationships of the C-terminal functional domain of hirudin and its variants
1Merrell Dow Research Institute, Cincinnati, OH 45215.
Insights
The C-terminal domain of hirudin significantly contributes to thrombin inhibition. Structure-function studies reveal distinct binding interactions among hirudin variants, impacting their anticoagulant efficacy.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Hirudin is a potent anticoagulant that inhibits thrombin.
- The C-terminal domain (residues 55-65) of hirudin is crucial for thrombin binding.
- This domain contributes significantly to the overall binding energy and inhibitory function.
Purpose of the Study:
- To investigate the structure-function relationships (SAR) of hirudin's C-terminal domain.
- To compare the thrombin interaction modes of hirudin and its variants.
- To understand how sequence variations affect binding affinity and anticoagulant activity.
Main Methods:
- Structure-function analysis of hirudin variants.
- Comparative analysis of binding interactions with thrombin.
- Evaluation of structure-activity relationships (SAR).
Main Results:
- The C-terminal domain provides approximately half of the binding energy for hirudin to thrombin.
- Hirudin and hirudin PA exhibit similar SAR profiles, suggesting comparable thrombin interaction modes.
- Hirullin P18, despite using the same binding domain, displays a different SAR, indicating an alternative interaction mechanism.
Conclusions:
- The C-terminal domain is a key determinant of hirudin's anticoagulant activity.
- Structural similarities and differences in hirudin variants lead to varied thrombin binding strategies.
- Understanding these interactions is vital for developing novel anticoagulants.
Abstract:
The C-terminal functional domain of hirudin, hirudin variant 1 (residues 55-65), binds to a non-catalytic site on thrombin. In doing so, it is capable of inhibiting the procoagulant actions of thrombin. In terms of free energy of binding, this domain, which comprises 17% of the total sequence of the protein, contributes approximately half of the binding energy of the whole protein to thrombin. This situation also appears to hold true for the known variants of hirudin, some of which differ in the functional nature of their C-terminal regions. Extensive structure-function studies on this domain yield insights into the differences and similarities in the modes of thrombin interaction of hirudin and its variants. In particular, hirudin and hirudin PA have a similar and somewhat interchangeable structure-activity relationships (SAR) profile that indicates that they interact with thrombin in a similar manner. Hirullin P18, a 62 amino acid member of the hirudin family and isolated from Hirudinaria manillensis, is substantially different in sequence and its SAR, which shows that, although it seems to utilize the same non-catalytic binding domain as hirudin, it must utilize a different mode of interaction with thrombin.