English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Bacteriorhodopsin mutants D85N, D85T and D85,96N as proton pumps

Tittor, J., Oesterhelt, D., & Bamberg, E. (1995). Bacteriorhodopsin mutants D85N, D85T and D85,96N as proton pumps. Biophysical Chemistry, 56(1-2), 153-157. doi:10.1016/0301-4622(95)00027-U.

Item is

Basic

show hide
Genre: Journal Article

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Tittor, Jörg1, Author           
Oesterhelt, Dieter1, Author           
Bamberg, Ernst2, Author           
Affiliations:
1Oesterhelt, Dieter / Membrane Biochemistry, Max Planck Institute of Biochemistry, Max Planck Society, ou_1565164              
2Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society, ou_2068289              

Content

show
hide
Free keywords: BLM; Retinal; Vectorial catalysis; Ion pump; Schiff base
 Abstract: Proton translocation in the BR mutants D85N, D85T and D85,96N was studied by attachment of purple membranes to planar lipid bilayers. Pump currents in these mutants were measured via capacitive coupling and by use of the appropriate ionophores. All mutants have a reduced pK of their Schiff bases around 8–8.5 in common. At physiological pH, a mixture of chromophores absorbing at 410 nm (deprotonated form) and around 600 nm (protonated form) coexists. Excitation with continuous blue light induces in all three mutants an outwardly directed stationary pump current. These currents are enhanced upon addition of azide in D85N and D85,96N by a factor of 50, but no azide enhancement is observed in D85T. Yellow light alone induces transient inwardly directed currents in the mutants but additional blue light leads to a stationary current with the same direction. All the observed currents are carried by protons, so that the consecutive absorption of a yellow and a blue photon leads to inverted stationary photocurrents by the mutants, as observed with halorhodopsin (HR). A mechanistic model describing the inversion of proton pumping is discussed by the cis-trans, trans-cis isomerization of the retinal and the different proton accessibility of the Schiff base from the extracellular or the cytoplasmic side of the membrane.

Details

show
hide
Language(s): eng - English
 Dates: 2000-04-041995-09
 Publication Status: Published in print
 Pages: 5
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1016/0301-4622(95)00027-U
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Biophysical Chemistry
  Other : Biophys. Chem.
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Amsterdam, Netherlands : Elsevier
Pages: - Volume / Issue: 56 (1-2) Sequence Number: - Start / End Page: 153-157 Identifier: ISSN: 0301-4622
CoNE: https://pure.mpg.de/cone/journals/resource/954925509389