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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Effects of As(III) binding on alpha-helical structure
Daniel J Cline1, Colin Thorpe, Joel P Schneider
1Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522, USA.
Journal of the American Chemical Society
|March 6, 2003
Summary
Arsenic(III) binding to cysteine residues in model peptides destabilizes alpha-helical structures, altering protein folding. Specific arrangements, like i, i+3, can eliminate helices, while i, i+4 arrangements stabilize them.
Area of Science:
- Biochemistry
- Structural Biology
- Chemical Biology
Background:
- Arsenic(III) has diverse cellular effects, but its impact on protein structure is not well understood.
- Cysteine residues are key binding sites for arsenic in biological systems.
Purpose of the Study:
- To investigate the structural consequences of arsenic(III) binding to alpha-helical peptides.
- To determine how the arrangement and location of cysteine residues influence arsenic binding and structural changes.
Main Methods:
- Circular dichroism (CD) spectroscopy was used to analyze peptide secondary structure.
- Model alpha-helical peptides with varying cysteine (Cys) residue arrangements were synthesized.
- Binding affinities and association rate constants were measured.
Main Results:
- Arsenic(III) binding destabilized helices when Cys residues were in central or C-terminal positions with i, i+1, i+2, or i+3 arrangements.
- Arsenic binding to i, i+3 positioned Cys residues eliminated helical structure, forming an alternate fold.
- Helical stabilization occurred for peptides with i, i+4 Cys residues, with measured interaction energies.
- As(III) binding affinity was largely insensitive to Cys location in moderately stable helices.
Conclusions:
- Arsenic(III) binding significantly modulates alpha-helical secondary structure.
- The spatial arrangement of cysteine residues dictates the structural outcome of arsenic binding.
- Understanding these interactions is crucial for comprehending arsenic's cellular mechanisms.
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