(191cz) Enhanced Enzyme Activity through Photoreversible Conformational Changes

Wang, Y., University of Southern california
The interaction of a light-responsive surfactant with catalase at pH 7.0 has been investigated as a means to control protein structure and enzymatic activity with light illumination. The cationic azobenzene surfactant undergoes a reversible photoisomerization upon exposure to the appropriate wavelength of light, with the visible-light (trans) form being more hydrophobic and, thus, inducing a greater degree of protein unfolding than the UV-light (cis) form. Conformational changes as a function of photoresponsive surfactant concentration and light illumination were measured through shape- reconstruction analysis of small-angle neutron scattering (SANS) data, dynamic light scattering data (DLS), circular dichroism (CD), and uv-vis spectrometry. The SANS data indicates that catalase is a native quaternary structure protein. In the presence of these surfactants, catalase disassociates into dimer, which is a super active structure. CD data shows changes in secondary structure associated with subunit dissociation. And uv-vis data provides evidence of structure changes of catalase when in presence of surfactant. Both structure change and super activity can be observed under trans light condition, and go back to native conditions upon exposure to UV light, thus leading to photoreversible control of the structure and function of catalase.