Protein functionalization is the process of modifying proteins or peptides to add new functionalities or properties. This can involve adding chemical groups, small molecules, or other biomolecules to the protein structure to enhance its stability, solubility, or activity. Protein functionalization is a key technique in protein engineering and bioconjugation, and is used in a wide range of applications, including drug delivery, diagnostics, and biotechnology. By modifying proteins in this way, researchers can create novel biomaterials with unique properties and functions.