Back to Search
Start Over
Structural transition of bacteriorhodopsin is preceded by deprotonation of Schiff base: microsecond time-resolved x-ray diffraction study of purple membrane
- Source :
- Biophysical journal. 88(1)
- Publication Year :
- 2004
-
Abstract
- The structural changes in the photoreaction cycle of bacteriorhodopsin, a light-driven proton pump, was investigated at a resolution of 7 angstroms by a time-resolved x-ray diffraction experiment utilizing synchrotron x rays from an undulator of SPring-8. The x-ray diffraction measurement system, used in coupling with a pulsed YAG laser, enabled us to record a diffraction pattern from purple membrane film at a time-resolution of 6 micros over the time domain of 5 micros to 500 ms. In the time domain, the functionally most important M-intermediate appears. A series of time-resolved x-ray diffraction data after photo-excitation showed clear intensity changes caused by the conformational changes of helix G in the M-intermediate. The population of the reaction intermediate was prominently observed at approximately 5 ms after a photo-stimulus. In contrast, absorption measurement indicated the deprotonation of the Schiff base predominantly occurred at approximately 300 micros after a photo-stimulus. These results showed that the conformational changes characterizing structurally the M-intermediate predominantly occur at a later stage of the deprotonation of the Schiff base. Thus, the M-intermediate can be divided into two metastable stages with different physical characteristics.
- Subjects :
- Diffraction
Halobacterium
Time Factors
Light
Protein Conformation
Population
Biophysics
chemistry.chemical_compound
Deprotonation
Purple Membrane
X-Ray Diffraction
education
Photobiophysics
Schiff Bases
Neutrons
education.field_of_study
Schiff base
biology
Fourier Analysis
Lasers
Resolution (electron density)
Bacteriorhodopsin
Protein Structure, Tertiary
Crystallography
Microsecond
chemistry
Bacteriorhodopsins
X-ray crystallography
biology.protein
Protons
Subjects
Details
- ISSN :
- 00063495
- Volume :
- 88
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Biophysical journal
- Accession number :
- edsair.doi.dedup.....e54e64c1337b79b08e722c24347909c8