KINETIC ANALYSIS OF TIME‐RESOLVED INFRARED DIFFERENCE SPECTRA OF THE L and M INTERMEDIATES OF BACTERIORHODOPSIN

Wei‐Ge ‐G Chen, Mark S Braiman

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Abstract– Infrared difference spectra with 4 cm−1 spectral resolution and 10‐u.s temporal resolution, obtained previously with a stroboscopic Fourier‐transform difference technique (Braiman et al., 1991, Proc. Natl. Acad. Sci. USA 88, 2388), were analyzed by means of a global exponential fitting procedure based on singular value decomposition. Using a simple linear kinetic model K → L → M for the bacteriorhodopsin (bR) photocycle in the time range10–1000 μ.s at 16.5°C, it was possible to generate bR → L and bR → M difference spectra with signal/noise ratios comparable to those obtainable with low temperature difference spectroscopy. The resulting time‐resolved bR → L and bR‐→ M difference spectra are both very similar to the corresponding static FTIR difference spectra obtained at 175 K and 250 K, respectively. In the bR → L spectrum, however, there are interesting differences that may indicate a greater degree of deprotonation of Asp‐96 when L is formed at physiological temperatures than when it is observed in a low‐temperature steady state.

Original languageEnglish (US)
Pages (from-to)905-910
Number of pages6
JournalPhotochemistry and Photobiology
Volume54
Issue number6
DOIs
StatePublished - 1991
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry
  • Physical and Theoretical Chemistry

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