Structure-based design of residue 1 analogs of the direct thrombin inhibitor pentapeptide FM 19
Elizabeth A Girnys1, Katarzyna Sobczyk-Kojiro, Henry I Mosberg
1Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA.
Insights
Researchers modified a thrombin inhibitor, FM 19, to improve its potency against alpha-thrombin. New compounds demonstrated enhanced inhibition, offering potential for new anticoagulant therapies targeting acute coronary syndromes.
Area of Science:
- Biochemistry
- Pharmacology
- Cardiovascular Research
Background:
- Acute coronary syndromes, often caused by thrombus formation in atherosclerotic arteries, are a major global health concern.
- Thrombin, a key enzyme in clot formation, is a significant target for anticoagulant and antithrombotic drug development.
- Previous lead compound FM 19 exhibited moderate thrombin inhibition, with X-ray crystallography revealing modification sites for enhanced potency.
Purpose of the Study:
- To improve the potency of the lead compound FM 19 as a thrombin inhibitor.
- To explore modifications at the first residue (D-Arg1) of FM 19 to address identified structural and electrostatic limitations.
- To design and synthesize novel compounds with potentially enhanced alpha-thrombin inhibitory activity.
Main Methods:
- Structure-based drug design utilizing X-ray crystallography data of thrombin-inhibitor complexes.
- Chemical synthesis of novel FM 19 analogs with modifications to the N-terminal residue.
- Biochemical assays to determine the inhibitory potency (IC50 values) of synthesized compounds against alpha-thrombin.
Main Results:
- Two novel compounds, designated 1 and 9, were synthesized and evaluated.
- Both compounds exhibited significantly improved inhibition of alpha-thrombin compared to the lead compound FM 19.
- Compound 1 showed an IC50 of 0.66 +/- 0.20 microM, and compound 9 showed an IC50 of 0.57 +/- 0.12 microM.
Conclusions:
- Modifications to the N-terminal D-Arg1 residue of FM 19 can effectively enhance alpha-thrombin inhibitory potency.
- The developed compounds represent promising candidates for further investigation as novel anticoagulant agents.
- These findings contribute to the development of targeted therapies for preventing and treating thrombotic cardiovascular diseases.
Abstract:
Myocardial ischemia and other acute coronary syndromes are leading causes of death worldwide, and often result from a thrombus that blocks an atherosclerotic coronary artery. A key enzyme in thrombus formation is the serine protease thrombin, which is responsible for both the conversion of soluble fibrinogen into insoluble fibrin, as well as the activation of the GPCRs, PAR1 and PAR4, which stimulate platelet aggregation. Thus, thrombin is an attractive target for anticoagulant and antithrombotic therapy. Previous studies in our laboratory led to the development of lead compound FM 19 (D-Arg-Oic-Pro-D-Ala-Phe(p-Me)-NH2), which shows modest potency as a thrombin inhibitor. The recently determined X-ray structure of FM 19 in the active site of thrombin has revealed potential sites for modification to improve potency. This study reports replacements to the first residue (D-Arg1) of FM 19, which seek to improve potency by removing the N-terminal amine to eliminate an adverse electrostatic interaction, and alterations to the length of the side chain to eliminate an unfavorable eclipsed conformation observed in the X-ray structure. This study produced two compounds, 1 and 9, with improved alpha-thrombin inhibition (IC50 values of 0.66 +/- 0.20 microM and 0.57 +/- 0.12 microM, respectively).
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