2026-10-12T11:46:20Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33985637 2026-09-24T13:05:46Z category_1 category_915 category_873 category_734 portal_63 item_type_2 month_year_09_2026

Coherent Vibrational Wave Packet Motion in ErCry4a Proteins Monitors the Redox State of the Flavin Chromophore Krishan Kumar (197868) Daniel Timmer (7329497) Maryam Khazani (25104134) Glen Dautaj (12320979) Sophie Brinkmann (25104137) Jan P. Götze (2063170) Peter Saalfrank (1351506) Boris F. Gribakin (25104140) Antonietta De Sio (7329500) Henrik Mouritsen (81010) Christoph Lienau (1361106) Biophysics Physical Sciences not elsewhere classified Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified sup >•–</ sup results provide insight flavin chromophore forms flavin chromophore cryptochromes coherent vibrational motion transfer processes initiated selective tryptophan mutation nearby tryptophan moiety play central roles lived radical pair transfer steps across nonadiabatic couplings play frequency vibrations persists cry4a proteins monitors subsequent electron transfer initial energy relaxation er </ italic charge transfer dynamics nonadiabatic couplings initial steps cry4a proteins er </ tryptophan residues electron transfer radical anion frequency excited state vibrations tetradic chain stimulated emission specific monitoring sensitive flavoproteins rapidly damped primary candidates optical excitation migratory songbirds independently validated general strategy formed fad european robin erithacus rubecula cryptochrome photoactivation central role biological function Cryptochromes are blue-light-sensitive flavoproteins that play central roles in biological function. In European robin (Erithacus rubecula) <i>Er</i>Cry4a proteins, optical excitation of their flavin chromophore forms a long-lived radical pair through a sequence of electron-transfer steps across a tetradic chain of tryptophan residues, making them primary candidates for magnetoreception in night-migratory songbirds. Recent quantum chemical calculations indicate that nonadiabatic couplings play a central role in the energy- and charge-transfer processes initiated by optical excitation. Here, we study these dynamics in <i>Er</i>Cry4a using ultrafast transient absorption spectroscopy with 10 fs time resolution in the 450 nm spectral range. We uncover a rapid, sub-50 fs red shift in stimulated emission, quenched within 360 fs by electron transfer from a nearby tryptophan moiety. While high-frequency excited-state vibrations are rapidly damped, coherent motion involving several low-frequency vibrations persists during both the initial energy relaxation and the subsequent electron transfer. This is evidenced by probing the coherent vibrational motion of the formed FAD^•– radical anion and is independently validated by blocking the electron transfer through site-selective tryptophan mutation. Our results provide insight into the role of nonadiabatic couplings for the initial steps of cryptochrome photoactivation and suggest a general strategy for redox-state-specific monitoring of charge transfer dynamics by probing coherent vibrational motion. 2026-09-24T00:00:00Z Dataset Media 10.1021/jacs.6c14527.s004 https://figshare.com/articles/media/Coherent_Vibrational_Wave_Packet_Motion_in_ErCry4a_Proteins_Monitors_the_Redox_State_of_the_Flavin_Chromophore/33985637 CC BY-NC 4.0