title: All-Optical Sensing of the Components of the Internal Local Electric Field in Proteins.
abstract: Here, we present a new all-optical method of interrogation of the internal electric field vector inside proteins. The method is based on experimental evaluation of the permanent dipole moment change upon excitation and the pure electronic transition frequency of a fluorophore embedded in a protein matrix. The permanent dipole moment change can be obtained from two-photon absorption measurements. In addition, permanent dipole moment change, tensor of polarizability change, and transition frequency for the free chromophore should be calculated quantum-mechanically. This allows obtaining the components of the electric field by considering the second-order Stark shift. We use the fluorescent protein mCherry as an example to demonstrate the applicability of the method.
authors.affiliation: Department of Physics, Montana State University, Bozeman, MT 59717 USA.
authors.forename: M
authors.initials: M
authors.lastname: Drobizhev
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Scott
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 USA.
authors.forename: P R
authors.initials: PR
authors.lastname: Callis
authors.affiliation: Department of Physics, Montana State University, Bozeman, MT 59717 USA.
authors.forename: A
authors.initials: A
authors.lastname: Rebane
keywords: Ultrafast nonlinear processes; biophotonics; electrochromism; fluorescence; light interaction; molecular biophysics; nonlinear effects; nonlinear optics; proteins; spectroscopy; spectroscopy of biological materials; stark effect; two-photon processes