Incorporation of non-natural amino acids into recombinant polypeptide chains opens a universe of new possibilities for engineering protein functions and properties. By incorporating p-benzoyl-L-phenylalanine into proteins, we can create a specific site for complex formation with β-CD, with stronger binding constants compared to native aromatic residues. The photochemical properties of benzophenone can be used to form a covalent bond with the β-CD host upon UV irradiation. We named this technique “Dock’n’Flash”1.
Idealized model for the site-specific complex formation between a non-natural benzophenone group in recombinant cutinase and a β-CD molecule coupled to a solid surface. Photo-excitation of benzophenone leads to photo-coupling to β-CD. (From Jensen et al, 2010).
In practice, this technique can be used to photocouple proteins to materials where β-CD cavities are accessible, like films on surfaces, polymeric matrices or molecules in solution. Photo-coupling reactions are fast, can be achieved in mild conditions compatible with protein structural and functional integrity and can be initiated in time and space with the use of laser beams.
We are currently investigating the molecular mechanisms of complex formation and photo-coupling of benzophenone-tagged proteins with β-CD or β-CD derivatives. Our goal is to optimize binding constants as well as photo-coupling yields in order to make “Dock’n’Flash” a useful and competitive technique for the immobilization of proteins to diverse materials.
- Jensen, R. L., Stade, L. W., Wimmer, R., Stensballe, A., Duroux, M., Larsen, K. L., Wingren, C., Duroux, L., 2010. Direct site-directed photocoupling of proteins onto surfaces coated with beta-cyclodextrins. Langmuir, 26, 11597-11604.