Engineering proteins with catechol chemistry for biotechnological applications.

Developing proteins with increased chemical space by expanding the amino acids alphabet has been an emerging technique to compete for the obstacle encountered by their need in various applications. 3,4-Dihydroxyphenylalanine (L-DOPA) catecholic unnatural amino acid is abundantly present in mussels foot proteins through post-translational modification of tyrosine to give a strong adhesion toward wet rocks. L-DOPA forms: bidentate coordination, H-bonding, metal-ligand complexes, long-ranged electrostatic, and van der Waals interactions via a pair of donor hydroxyl groups. Incorporating catechol in proteins through genetic code expansion paved the way for developing: protein-based bio-sensor, implant coating, bio-conjugation, adhesive bio-materials, biocatalyst, metal interaction and nano-biotechnological applications. The increased chemical spaces boost the protein properties by offering a new chemically active interaction ability to the protein. Here, we review the technique employed to develop a genetically expanded organism with catechol to provide novel properties and functionalities; and we highlight the importance of L-DOPA incorporated proteins in biomedical and industrial fields.