Research on the transition dynamics and linear (nonlinear) optical properties of mCherry
In this study, we explore the electron transition mechanism and optical properties of the popular red fluorescent protein mCherry. By examining the charge transfer spectrum and combining it with the mCherry hole-electron distribution, we identify that the charge transfer between the phenolate and imidazolinone loops significantly contributes to the absorption spectrum. Quantitative analysis of charge transfer shows that, overall, the electrons are transferred to the C16 atom in the middle of phenolate and the imidazolinone loops during absorption. We speculate that C16 may also absorb protons to enable the photoconversion of mCherry in the excited state, similar to the blinking mechanism of IrisFP. In addition, we further investigated the optical properties of mcherry in the external field by polarizability (hyperpolarizability), showing the anisotropy of the polarization, the first hyperpolarization and the second hyperpolarization by unit spherical representation. Our results suggest that significant polarization and second hyperpolarizability occur when the field direction and electron transfer direction are aligned. We also analyzed the polarizability and first hyperpolarizabilities for different external fields. The polarizability mutated when the external field satisfies the S_0,min-> S_1 transition. Finally, the study of the first hyperpolarizability shows that adjusting the appropriate field can lead to a linear photoelectric effect or second harmonic generation of mCherry. These studies have certain reference values for various red fluorescent protein correlation simulations and experiments because of the similarity of the red fluorescent protein.