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MTD-ADJ: a multiconformational minimal topologic difference for determining bioactive conformers using adjusted
T Sulea1, L Kurunczi, T I Oprea
1FORSLYS (The Group for the Formal Study of Living Systems), Timisoara, România.
Journal of Computer-Aided Molecular Design
|August 5, 1998
Summary
This study introduces an adjusted quantitative structure-activity relationship (QSAR) method to better understand ligand-receptor interactions. The adjusted method refines models for acetylcholinesterase inhibitors, revealing insights into active conformations.
Area of Science:
- Computational Chemistry
- Medicinal Chemistry
- Structural Biology
Background:
- Quantitative structure-activity relationship (QSAR) studies often simplify ligand-receptor interactions by assuming a single active conformation.
- Accounting for the conformational mixture of ligands is crucial for accurate modeling of biological activity.
- Acetylcholinesterase (AChE) is a key target for treating Alzheimer's disease and other conditions.
Purpose of the Study:
- To develop and validate an adjusted multiconformational minimal steric/topologic difference (MTD-ADJ) method for 3D-QSAR.
- To refine the understanding of ligand-receptor interactions by incorporating the relative abundance of active conformations.
- To propose a binding site model for neutral ligands interacting with AChE.
Main Methods:
- Utilized an adjusted quantitative structure-activity relationship (QSAR) approach, termed MTD-ADJ, to analyze acetylcholinesterase (AChE) hydrolysis rates.
- Adjusted experimental activity (Yexp) using the relative amount (alpha) of active conformations: Yadj = Yexp - log alpha.
- Calculated relative energies using AMI (MOPAC 6.0) and Boltzmann distribution for conformer weighting, with conformers derived from COSMIC 90.
Main Results:
- The MTD-ADJ models demonstrated significant statistical parameters, comparable to unadjusted models (MTD-MC).
- Identified bioactive conformations as extended and occupying cavity vertices within the AChE active site.
- The optimized conformational map from MTD-ADJ showed good fit with the crystallographic structure of AChE.
Conclusions:
- The MTD-ADJ method effectively incorporates conformational flexibility, providing enhanced insights into ligand-receptor interactions.
- The study proposes a novel binding site model for neutral ligands at the AChE active site.
- MTD-ADJ is a versatile tool applicable to various 3D-QSAR methods, especially when structural data is limited.