Cationic imidazolium macrocycles enable array-based, site-selective optical detection of peptide phosphorylation.

Area of Science:

• Chemical Biology
• Supramolecular Chemistry

Background:

• Peptide phosphorylation is crucial in cell signaling.
• Selective detection of phosphorylated sites remains challenging.

Purpose of the Study:

• To develop a novel method for site- and state-selective optical detection of peptide phosphorylation.
• To utilize polycationic imidazolium macrocycles and styrylpyridinium dyes for this purpose.

Main Methods:

• Synthesis of simple polycationic imidazolium macrocycles from commercial precursors.
• Pairing macrocycles with styrylpyridinium dyes in an arrayed format.
• Investigating interactions via complex equilibrium analysis.

Main Results:

• Polycationic macrocycles exhibit strong affinity for anionic and hydrophobic peptide strands.
• Detection relies on π-stacking interactions with the peptide backbone and sidechains, not direct phosphate binding.
• Complex equilibria involving peptide:host, peptide:dye, and dye:host assemblies, including ternary complexes, enable differentiation.
• Successful differentiation of phosphorylation at different sites on identical peptide strands.

Conclusions:

• The developed system enables site- and state-selective optical detection of serine phosphorylation.
• The method leverages supramolecular interactions for sensitive peptide analysis.
• This approach offers a new tool for studying phosphorylation-dependent biological processes.