BATHORHODOPSIN STRUCTURE IN THE ROOM-TEMPERATURE RHODOPSIN PHOTOSEQUENCE - PICOSECOND TIME-RESOLVED COHERENT ANTI-STOKES-RAMAN SCATTERING

Structural changes in the retinal chromophore during the formation of the bathorhodopsin intermediate (batho(RT)) in the room-temperature rh odopsin (Rh-RT) photosequence (i.e., vision) are examined using picose cond time-resolved coherent anti Stokes Raman scattering, Specifically , the retinal structure assignable to batho(RT) following 8-ps excitat ion of Rh-RT is measured via vibrational Raman spectroscopy at a 200-p s time delay where the only intermediate present is batho(RT), Signifi cant differences are observed between the C=C stretching frequencies o f the retinal chromophore al low temperature where bathorhodopsin is s tabilized and at room temperature where bathorhodopsin is a transient species in the Rh-RT photosequence. These vibrational data are discuss ed in terms of the formation of batho(RT), an important step in the en ergy storage/transduction mechanism of Rh-RT.