National Center for
4YGG: Crystal Structure Of R111k:y134f:t54v:r132q:p39y:r59y Mutant Of Human Cellular Retinoic Acid Binding Protein Ii With Retinal At 1.9 Angstrom Resolution - Visible Light Irradiated Crystal - 2nd Cycle
J. Am. Chem. Soc. (2016) 138 p.8802-8808
The members of the rhodopsin family of proteins are involved in many essential light-dependent processes in biology. Specific photoisomerization of the protein-bound retinylidene PSB at a specified wavelength range of light is at the heart of all of these systems. Nonetheless, it has been difficult to reproduce in an engineered system. We have developed rhodopsin mimics, using intracellular lipid binding protein family members as scaffolds, to study fundamental aspects of protein/chromophore interactions. Herein we describe a system that specifically isomerizes the retinylidene protonated Schiff base both thermally and photochemically. This isomerization has been characterized at atomic resolution by quantitatively interconverting the isomers in the crystal both thermally and photochemically. This event is accompanied by a large pKa change of the imine similar to the pKa changes observed in bacteriorhodopsin and visual opsins during isomerization.