Anion-Binding Properties of Short Linear Homopeptides
Matija Modrušan1, Lucija Glazer1, Lucija Otmačić1
1Department of Chemistry, Faculty of Science, Horvatovac 102a, 10000 Zagreb, Croatia.
International Journal of Molecular Sciences
|May 25, 2024
Summary
Linear peptides like tetra-, penta-, and hexaphenylalanine bind inorganic anions, forming 1:1 complexes. This anion binding induces structural changes, aiding cyclopeptide synthesis and enabling ionophore activity.
Area of Science:
- Supramolecular Chemistry
- Peptide Chemistry
- Anion Recognition
Background:
- Linear peptides are increasingly studied for their potential in molecular recognition and self-assembly.
- Understanding peptide-anion interactions is crucial for developing novel sensors, catalysts, and drug delivery systems.
- The influence of peptide chain length on binding thermodynamics and structural dynamics remains an active area of research.
Purpose of the Study:
- To investigate the complexation affinities of linear polyphenylalanine peptides (L1-L3) with various inorganic anions.
- To elucidate the thermodynamic parameters and structural consequences of anion binding in different solvent environments (acetonitrile and DMF).
- To explore the potential of these peptides as ionophores for transmembrane anion transport.
Main Methods:
- Complexation studies using spectrofluorimetric, 1H NMR, microcalorimetric, and circular dichroism spectroscopy titrations.
- Stoichiometry determination of peptide-anion complexes.
- Molecular dynamic simulations to analyze anion-induced conformational changes in peptide backbones.
Main Results:
- All three peptides (L1-L3) formed stable 1:1 complexes with chloride, bromide, hydrogen sulfate, dihydrogen phosphate (DHP), and nitrate anions.
- Higher order complexes (1:2 and 2:1 peptide:anion) were observed for hydrogen sulfate and DHP anions.
- Anion binding induced a conformational shift from elongated to quasi-cyclic structures in the peptide backbone via hydrogen bonding.
Conclusions:
- Linear polyphenylalanine peptides exhibit significant affinities for inorganic anions, with binding influenced by peptide length and solvent.
- Anion binding triggers specific conformational changes in the peptide backbone, favoring a quasi-cyclic structure crucial for macrocyclization in peptide synthesis.
- These peptides demonstrate potential as versatile ionophores for facilitating anion transport across membranes.
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