2016: Femtosecond infrared spectroscopy of channelrhodopsin-1 chromophore isomerization

Structural Dynamics 3, 043208 (2016);

Vibrational dynamics of the retinal all-trans to 13-cis photoisomerization in
channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) was investigated by
femtosecond visible pump mid-IR probe spectroscopy. After photoexcitation, the
transient infrared absorption of C-C stretching modes was detected. The formation
of the 13-cis photoproduct marker band at 1193 cm-1 was observed within the time
resolution of 0.3 ps. We estimated the photoisomerization yield to (60±6) %. We
found additional time constants of (0.55±0.05) ps and (6±1) ps, assigned to
cooling, and cooling processes with a back-reaction pathway. An additional
bleaching band demonstrates the ground-state heterogeneity of retinal.

doi: 10.1063/1.4948338