Metallo-coiled Coil Stabilization via Chemical Cross-Linking: Implications for Gd(III)-Based MRI Contrast Agents

Area of Science:

• Protein engineering
• Biophysical chemistry
• Materials science

Background:

• Coiled coils are versatile protein-inspired ligands for diverse applications.
• Their utility is limited by poor stability, especially under physiological conditions.

Purpose of the Study:

• To enhance the stability of lanthanide-bound coiled coils using covalent interhelical isopeptide cross-linking.
• To develop improved MRI contrast agents.

Main Methods:

• Covalent interhelical isopeptide cross-linking strategy.
• Biophysical analyses: CD, native MS, HPLC, fluorescence assays.
• ¹H relaxometric studies and molecular dynamics simulations.

Main Results:

• Cross-linking significantly enhanced thermal, thermodynamic, kinetic, and proteolytic stability.
• A 2.5 × 10⁸-fold increase in metal-binding affinity was observed.
• Optimized cross-linking improved MRI efficacy by approximately 30%.

Conclusions:

• Covalent cross-linking is a viable strategy to enhance metallo-coiled coil stability and function.
• This approach holds promise for developing advanced MRI contrast agents.
• The findings broaden the potential applications of cross-linked metallo-coiled coils.