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Updated: May 2, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Excited-State Mixing in the LOV Domain Proteins: Possible Physics behind the Difference in the Transient Absorption
Yingliang Liu1,2,3, Aditya S Chaudhari1, Alessandra Picchiotti2,4
1Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
Abstract:
It remains uncertain whether excited electronic state mixing occurs in the flavin cofactor of the light-oxygen-voltage-sensing (LOV) domain. In this study, we present transient absorption and femtosecond stimulated Raman spectra of both free and EL222 binding flavin mononucleotide (FMN). We observed a change in the shape of the excited-state absorption around 800 nm in the S1 state transient absorption after binding to EL222, alongside a relative intensity increase of the N1-C2 and C2═O2 stretching modes in the S1 state Raman spectra. Based on the previous calculated geometric differences between the ππ* and nπ* states, we propose a probable electronic state mixing in EL222 binding FMN. This mixing is favored by the nonsymmetric hydrogen bonding interaction between the flavin O4 atom and the asparagine residue and fewer hydrogen bonds with the O2 atom in EL222.
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