3-Acyl-4-Pyranone as a Lysine Residue-Selective Bioconjugation Reagent for Peptide and Protein Modification

Area of Science:

• Bioconjugation Chemistry
• Chemical Biology
• Medicinal Chemistry

Background:

• Chemoselective protein modification is crucial for biological, medical, and pharmaceutical research.
• Natural azaphilones react with primary amines but have limitations in solubility and application.

Purpose of the Study:

• To develop simplified, highly soluble chemical tools for selective protein modification.
• To mimic the reactivity of azaphilones using a more accessible pyranone scaffold.
• To enable versatile protein functionalization and explore its impact on enzyme activity.

Main Methods:

• Simplified azaphilone scaffolds into 3-acyl-4-pyranones.
• Evaluated the reactivity and selectivity of pyranones towards primary amines (lysine residues).
• Assessed aqueous solubility and reaction kinetics (second-order rate constant).
• Utilized pyranones in combination with copper-catalyzed azide-alkyne Click chemistry for protein decoration.
• Modified lysozyme with charged functionalities and assessed changes in enzymatic activity.

Main Results:

• 3-acyl-4-pyranones effectively mimic azaphilone reactivity for selective conjugation with primary amines.
• The pyranone tool exhibits enhanced aqueous solubility and a compatible rate constant compared to azaphilones.
• Biorthogonal conjugation with Click chemistry was achieved, allowing parallel decoration of lysozyme with diverse charges.
• Lysozyme modification with quaternary ammoniums enhanced enzymatic activity.

Conclusions:

• Simplified pyranone molecules provide a versatile and efficient platform for chemoselective protein modification.
• The enhanced properties and biorthogonal compatibility of pyranones expand their utility in chemical biology and drug discovery.
• Targeted protein modification can modulate protein function, as demonstrated by increased lysozyme activity.