ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Electric field induced conformational changes of bacteriorhodopsin in purple membrane films (1986)
    Springer
    European biophysics journal 13 (1986), S. 273-280 
    Details
    ISSN: 1432-1017
    Keywords: Bacteriorhodopsin ; blue membrane ; purple membrane films ; electric field-induced states ; electric dichroism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Electric field-induced absorption changes of bacteriorhodopsin were studied with different samples of purple membranes which were prepared as randomly oriented and electrically oriented films of purple as well as cation-depleted blue bacteriorhodopsin. The absorption changes were proportional to the square of the field strength up to ≈300 kV/cm. The electric field from the intracellular side to the extracellular side of the purple bacteriorhodopsin induces a spectrum change, resulting in a spectrum similar to that of the cation-depleted blue bacteriorhodopsin. When the field was removed, the purple state was regenerated. The blue state was mainly affected by an electric field in the opposite direction, suggesting a reversible interaction with the Schiff's base bond of the retinal. Since the field-induced reaction of bacteriorhodopsin was observed in the presence of a concomitant steady ion flux, it is assumed that the generation of a local diffusion potential may play an important role in these spectral reactions. Although the fragments were fixed in the dried film, electric dichroism was observed. The dichroic contribution of the total absorbance change was about 15%. The angular displacement of the retinal transition moment was calculated to be 1.5° toward the membrane normal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254209
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Electrooptical analysis of blue and of cation-regenerated bacteriorhodopsin (1987)
    Springer
    European biophysics journal 15 (1987), S. 231-236 
    Details
    ISSN: 1432-1017
    Keywords: Bacteriorhodopsin ; blue membrane ; purple membrane ; electric dichroism ; cation binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Blue bacteriorhodopsin was prepared by electrodialysis, cation-exchange chromatography and acidification. The electrooptical properties of these preparations compared to those of the native purple bacteriorhodopsin suggest that the blue bacteriorhodopsin has a smaller induced dipole moment than the native purple bacteriorhodopsin and that bound cations in the native bacteriorhodopsin stabilize the protein conformation in the membrane. Purple bacteriorhodopsin was regenerated by addition of potassium, magnesium or ferric ions to blue bacteriorhodopsin. Both spectrscopically and electrooptically the potassium- and ferric-regenerated samples are different from the native purple state. Although the magnesium-regenerated sample is spectroscopically similar to the native purple bacteriorhodopsin, the electrooptical properties are rather similar to those of the cation-depleted blue sample, suggesting that it is very difficult to re-stabilize protein structures once cations are depleted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00577071
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Electric field induced conformational changes of bacteriorhodopsin in purple membrane films (1988)
    Springer
    European biophysics journal 15 (1988), S. 329-337 
    Details
    ISSN: 1432-1017
    Keywords: Bacteriorhodopsin ; blue membrane ; purple membrane films ; electric-field-induced states ; dielectric dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Electric field induced conformational changes of bacteriorhodopsin were studied in six types of dried film (randomly and electrically oriented membranes of purple as well as cation-depleted blue bacteriorhodopsin) by measuring the frequency dependence of the optical absorbance change and the dielectric dispersion and absorption. For the purple bacteriorhodopsin the optical absorbance change induced by alternating rectangular electric fields of ±300 kV/cm altered the sign twice in the frequency range from 0.001 Hz to 100 kHz (around 0.03 Hz and 100 kHz), indicating that the electric field induced conformational change in these samples consists of, at least, three steps. Similarly, it was found for the blue bacteriorhodopsin that at least two steps are involved. In accord with optical measurements, the dielectric behaviour due to alternating sinusoidal electric fields of±6kV/cm in the frequency range from 10 Hz to 10 MHz showed two broad dispersion/absorption regions, one below 1 kHz and the other around 10–100 kHz. This suggests that the conformational change of bacteriorhodopsin is also reflected by its dielectrical properties and that it is partially induced at 6 kV/cm. Including previous results obtained by analysis of the action of DC fields on purple membrane films, a model for a field-induced cyclic reaction for purple as well as blue bacteriorhodopsin is proposed. In addition it was found that there are electrical interactions among purple membrane fragments in dried films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254720
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...