Inducing α-Helicity in Peptides by Silver Coordination to Cysteine

Area of Science:

• Biochemistry
• Structural Biology
• Materials Science

Background:

• Peptide secondary structure is crucial for biological function.
• Controlling peptide folding and assembly remains a challenge.

Purpose of the Study:

• To investigate the effect of silver ions (Ag+) on short peptide sequences.
• To explore the potential of silver-mediated interactions for peptide stabilization and assembly.

Main Methods:

• Far-UV circular dichroism spectroscopy to monitor secondary structure changes.
• Electrospray mass spectrometry (MS) to analyze complex formation.
• Potentiometric experiments for complex modeling.

Main Results:

• Short CXXXC peptides undergo a complete transition from random coil to alpha-helix upon Ag+ addition.
• The resulting CXXXC/Ag+ complex is stable over a broad pH range (3-8) and resistant to HPLC and physiological chloride levels.
• Complexes observed include peptide dimers with multiple Ag+ ions, with modeling supporting multinuclear silver species.
• The complex acts as a nucleation site for inducing alpha-helicity in longer peptides.

Conclusions:

• Silver ions can effectively mediate peptide folding and assembly.
• This silver-mediated mechanism offers a novel approach for stabilizing peptide structures and controlling oligomerization.
• Potential applications in peptide stabilization and controlled assembly, even under acidic conditions.