Biomacromolecules, Vol.6, No.1, 475-482, 2005
Enhancing enzyme stability against TiO2-UV induced inactivation
The use of enzymes in conjunction with inorganic photocatalysts requires stability against photooxidation. In this paper, we describe enhanced stabilization of a model enzyme, chymotrypsin, to photooxidation driven by titanium dioxide exposed to ultraviolet light (TiO2-UV). Stabilization is achieved conjugating the enzyme with an oligomeric adduct of UV-absorbing (2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate) (HBMA) and free radical-absorbing 2-methacryloyloxyethyl-6-hydroxy-2,5,7,8-tetramethylchroman-2carboxylate (Trolox-HEMA). Juxtaposition of the antioxidant Trolox with the UV absorber HBMA within a single chain reduced the rate of deactivation of the former by TiO2-UV. This enables modified enzyme, which is adsorbed on TiO2, to absorb both UV-light and free radicals and locally reduce the rate of photooxidation. Interestingly, Trolox was more readily deactivated by TiO2-UV when it was conjugated separately to chymotrypsin that had been pre-modified with HBMA moieties.