Time-resolved protein fluorescence studies of intermediates in the photochemical cycle of bacteriorhodopsin

Journal Article · Thu Jan 01 00:00:00 EST 1981 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.78.1.252· OSTI ID:6579676

Fukumoto, J M; Hopewell, W D; Karvaly, B; El-Sayed, M A

The photolysis-induced changes in the protein fluorescence intensity(at 320 nm) during the proton-pumping cycle of bacteriorhodopsin were examined by a delayed two-pulse technique in the time range 1 ..mu..sec-20 msec at room temperature. No detectable change in the protein fluorescence intensity was observed on the earliest time scale within the lifetime of the intermediate K/sub 590/, when retinal apparently undergoes the largest structural changes. The time dependence of the relative changes in fluorescence intensity did, however, display a close correlation with the population of L/sub 550/ and M/sub 412/ intermediates. From a computer numerical fit of the data, with available published kinetic parameters, the protein fluorescence quantum yields of the K/sub 590/, L/sub 550/, and M/sub 412/ intermediates are found to be 1.0, 0.92, and 0.80 of that for native bR/sub 570/, respectively. The probable mechanisms of the observed fluorescence quenching during the photochemical cycle are qualitatively discussed.

• Research Organization: Univ. of California, Los Angeles, CA (United States)
• OSTI ID: 6579676
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 78:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PHOTOCHEMICAL REACTIONS
BIOCHEMICAL REACTION KINETICS
PIGMENTS
STRUCTURAL CHEMICAL ANALYSIS
BACTERIA
BIOLOGICAL EFFECTS
BIOPHOTOLYSIS
CELL MEMBRANES
CHEMICAL PREPARATION
FLUORESCENCE
INTERMEDIATE STRUCTURE
TEMPERATURE DEPENDENCE
BIOCONVERSION
CELL CONSTITUENTS
CHEMICAL REACTIONS
DECOMPOSITION
KINETICS
LUMINESCENCE
MEMBRANES
MICROORGANISMS
PHOTOLYSIS
REACTION KINETICS
SYNTHESIS
550200* - Biochemistry
550700 - Microbiology