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Development of potent thrombin receptor antagonist peptides
M S Bernatowicz1, C E Klimas, K S Hartl
1Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543, USA.
Journal of Medicinal Chemistry
|December 6, 1996
Summary
Researchers developed novel, potent thrombin receptor antagonists by modifying peptide sequences. These new compounds, including BMS-197525 and BMS-200261, show significant potential for therapeutic applications by selectively blocking receptor activity.
Area of Science:
- Medicinal Chemistry
- Pharmacology
- Biochemistry
Background:
- The human thrombin receptor plays a crucial role in platelet aggregation and other physiological processes.
- Existing antagonists for the thrombin receptor have limited potency and require further optimization.
- Structure-activity relationship (SAR) studies are essential for designing effective peptide-based therapeutics.
Purpose of the Study:
- To discover and characterize novel, potent thrombin receptor antagonists through systematic peptide modification.
- To investigate the SAR of modified peptide sequences targeting the thrombin receptor's tethered ligand.
- To identify lead compounds with enhanced antagonist potency and selectivity for potential therapeutic use.
Main Methods:
- Systematic substitution of non-proteogenic amino acids in the human thrombin receptor tethered ligand sequence (SFLLR).
- Synthesis and evaluation of peptide analogs for agonist and antagonist activity, including EC50 and IC50 determinations.
- Radioligand binding assays and secondary assays (GTPase activity, Ca2+ mobilization) to confirm antagonist specificity.
Main Results:
- Discovery of potent pentapeptide agonists, with compound 9 exhibiting a 10-fold increase in potency over the natural ligand.
- Development of highly potent tetrapeptide antagonists, such as BMS-197525 (41), with over 1000-fold increased potency compared to previous antagonists.
- Identification of extended analogs, BMS-200261 (90) and BMS-200661 (91), demonstrating superior binding affinity and inhibitory activity.
- Confirmation of specific thrombin receptor antagonism, distinct from thrombin catalytic inhibition, through various biochemical assays.
Conclusions:
- Systematic SAR studies successfully yielded novel and highly potent thrombin receptor antagonists.
- Specific amino acid substitutions, particularly at the second and third positions and the N-terminus, are critical for antagonist potency.
- The identified compounds, such as BMS-197525 and BMS-200261, represent promising leads for developing new antithrombotic therapies.