Red-edge-excitation spectroscopy and protein dynamics control of intramolecular electron transfer in bianthryl

摘要

We report on excitation wavelength dependence of electron transfer reaction in bianthryl (BA) molecule bound by human serum albumin (HSA). The rate of this reaction is known to be controlled by the dynamics of the probe dielectric environment and, if the dynamic is slow in comparison with excited-state lifetime, by site-dependent photoselection at the red edge of BA absorption spectrum. In BA-HSA complex in the temperature range 10 - 40$DGR@C we observe the absence of electron transfer at the main band and its high effectiveness at red-edge excitation. These results demonstrate that the distribution on protein-probe interaction energy is of substantial width and the local dynamics in the binding site is slower than a nanosecond. This distribution and slow dynamics are definitely the origins of inhomogeneous kinetics of the electron transfer reaction.