Synthetic modifications of proteins
In the pursuit to develop new biohybrid materials based on protein structures or peptides, peptide chemistry is a convenient approach. In addition to conventional peptide chemistry in which reactive amino acids located on the protein surface are targeted, over the past few years many new approaches have been developed. Not only new reactions able to target the protein chemically but also other disciplines such as polymer chemistry and biocatalysis are now being added to the ever-broadening portfolio of protein/peptide alterations. Lysozyme, bovine serum albumin (BSA), ferritin and proteases such as chymotrypsin are examples that have been modified via the presented approaches. Hybrid conjugates with polymers or nanoparticles, for example, can be achieved not only by covalent linkages but also by non-covalent interactions. New tools introduced into the 'chemical toolbox' to modify protein structures, including controlled radical polymerization [especially atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT)] and 'click' reactions, are now commonly used to create bionanoparticle-based conjugates with new functionalities and hence associated with it new materials and applications.