Differences in heavy metal binding to cysteine-containing coiled-coil peptides

Area of Science:

• Biochemistry
• Structural Biology
• Bioinorganic Chemistry

Background:

• Approximately one-third of characterized proteins incorporate metals, yet the precise relationship between metal binding and protein folding remains incompletely understood.
• Investigating metal-peptide interactions is crucial for elucidating fundamental principles of protein structure and function.

Purpose of the Study:

• To explore how metal binding influences peptide folding and assembly.
• To compare the metal-binding properties of two distinct peptide scaffolds, CX3C and CX2C, designed to interact with heavy metal ions.

Main Methods:

• Utilized circular dichroism (CD) spectroscopy, UV-Vis spectroscopy, and size-exclusion chromatography coupled to multi-angle light scattering (SEC-MALS).
• Analyzed the structural and binding characteristics of CX3C and CX2C peptides in their apo state and upon addition of Cd(II), Pb(II), and Hg(II).

Main Results:

• Both CX3C and CX2C peptides, initially unfolded, adopt helical assemblies upon binding Cd(II), Pb(II), and Hg(II).
• Peptide scaffolds exhibit differential affinities for metal ions, influenced by ion size.
• Observed variations in oligomerization states and metal ion coordination geometries between the CX3C and CX2C peptide complexes.

Conclusions:

• Minor alterations in peptide primary structure can profoundly affect metal-binding capabilities.
• The study highlights the intricate interplay between peptide sequence, metal ion properties, and resulting structural outcomes.