Photocontrol of biological activities of protein by means of a hydrogel.

Because proteins show high activity and are essential for biological function, proteins are important and useful biomolecules; however, it is hard to control activities whenever and wherever required. Although some photoactivated proteins have been reported to date, such proteins have required a protein-specific design and site-specific chemical modification. We have recently developed a method to encapsulate proteins within hydrogels that can be photocleaved with ultraviolet (UV) light, thus releasing the proteins; we refer to this method as "protein activation and release from cage by external light (PARCEL)." Biological activities of protein restricted by hydrogel encapsulation were recovered by applying external light to the protein-hydrogel. We also used these hydrogels to screen selective ligands as therapeutic agents for disease. This innovative technique for basic research in biology and biochemistry might also be useful in practical or clinical applications, such as biosensing, catalysis, and drug delivery.