Femtosecond infrared spectroscopy of channelrhodopsin-1 chromophore isomerization

摘要

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.