Investigating Microenvironmental Conditions on A Biomolecular Chromophore

Photosynthetic pigments use every absorbed photon to initiate charge separation; however, the mechanisms that drive such high efficiency remain poorly understood. Effects from the local physicochemical environment on photosynthetic pigments likely influence efficiency, yet dissection of these contributions is challenging due to the complexity of the in vivo molecular environment. To better understand microenvironmental effects, we are studying a model biomolecular chromophore - the red, monomeric fluorescent protein mCherry - in the nanoscale water pool of reverse micelles. Reverse micelles are spontaneously organizing mixtures of surfactant, water, and nonpolar bulk solvent that can encapsulate proteins, thereby functioning as nanoscale labs for manipulation of local physicochemical solvation properties. The reverse micelles provide a controllable microenvironment, whereby the fluorescent efficiency of mCherry can be measured as a function of the reverse micelle composition. Our data reveal that the encapsulation of mCherry in reverse micelles increases its quantum yield in comparison to bulk aqueous solution. Data on the physicochemical underpinnings of this effect are also presented.