Аннотация:Linear optical response of the orange carotenoid protein (OCP) and
its mutants was successfully simulated by applying the Differential evolution
(DE) algorithm. OCP is a pigment-protein complex, which plays an important
role in non-photochemical quenching of excitation energy in photosynthetic
light-harvesting complexes in cyanobacteria. It contains a single carotenoid
pigment molecule surrounded by protein matrix. This pigment is entirely
responsible for OCP absorption in the region of 350–600 nm. To calculate the
OCP absorption spectra, we used the Multimode Brownian oscillator model
considering four high vibronic modes (m1, m2, m3 and m4) and one low frequency
mode. The frequencies of these modes were estimated from the OCP Raman
spectra; whereas the Huang-Rhys factors alongside the carotenoid electronic
transition and the FWHM of inhomogeneous broadening and the low frequency
mode were fitted by DE. It was show that characteristic features of OCP
absorption spectra can be explained by mutual variations of Huang-Rhys factors
of m1 and m2 that is corresponded to the in-phase stretching of C = C and C-C
bonds.