Vibrational spectrum of k-590 containing {sup 13}C{sub 14.15} retinal: Picosecond time-resolved coherent anti-Stokes Raman spectroscopy of the room temperature bacteriorhodopsin photocycle
- Univ. of Arizona, Tucson, AZ (United States)
- Weizmann Inst. of Science, Rehovot (Israel)
- Hebrew Univ., Jerusalem (Israel)
The C-C stretching vibrations (1100-1400 cm{sup -1}) of the K-590 intermediate (containing a {sup 13}C{sub 14,15} retinal), formed during the room-temperature (RT) bacteriorhodopsin (BR) photocycle, are measured using picosecond time-resolved coherent anti-Stokes Raman scattering (PTR/CARS). These PTR/CARS data are first time-resolved vibrational spectra from a picosecond BR intermediate at RT containing an isotopically-labeled ({sup 13}C) retinal. The C{sub 14} and C{sub 15} positions are selected for isotopic labeling because motions around the C{sub 13}=C{sub 14} and C{sub 14}-C{sub 15} bonds are thought to underlie the structural transformation from BR-570 to K-590 and, therefore, the energy storage and transduction mechanism in the RT/BR photocycle. Comparisons of these PTR/CARS data at RT with the results from earlier resonance Raman (RR) studies of K-590 at low temperature (LT) reveal new temperature effects. Analogous temperature-dependent differences are found in data measured from {sup 13}C{sub 14,15} K-590 in D{sub 2}O samples. Independently, PTR/CARS data at RT demonstrate that deuteration of the Schiff-base nitrogen causes major changes in the fingerprint region. No such deuterium effect is observed in the LT/RR date from {sup 13}C{sub 14,15} K-590. The previously unrecognized sensitivity of fingerprint bands to deuteration of the Schiff-base nitrogen suggests that the C-C stretching modes are highly mixed with each other and coupled to the N-H(D) retinal rocking mode. 57 refs., 7 figs., 3 tabs.
- OSTI ID:
- 380815
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 29 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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