Alternative translocation of protons and halide ions by bacteriorhodopsin

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.11.4751· OSTI ID:5200923

Der, A; Szaraz, S; Toth-Boconadi, R; Tokaji, Z; Keszthelyi, L; Stoeckenius, W ^[1]

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1. Univ. of California, San Francisco (USA)

Bacteriorhodopsin (bR568) in purple membrane near pH 2 shifts its absorption maximum from 568 to 605 nm forming the blue protein bRacid605, which no longer transports protons and which shows no transient deprotonation of the Schiff base upon illumination. Continued acid titration with HCl or HBr but not H2SO4 restores the purple chromophore to yield bRHCl564 or bRHBr568. These acid purple forms also regain transmembrane charge transport, but no transient Schiff base deprotonation is observed. In contrast to bR568, no rate decrease of the bRacidpurple transport kinetics is detected in 2H2O; however, the transport rate decreases by a factor of {approximately} 2 in bRHBr568 compared with bRHCl564. The data indicate that in the acid purple form bR transports the halide anions instead of protons. The authors present a testable model for the transport mechanism, which should also be applicable to halorhodopsin.

• OSTI ID: 5200923
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 88:11; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIONS
BARYONS
BIOLOGICAL FUNCTIONS
CHARGED PARTICLES
DEUTERIUM
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN ISOTOPES
IMINES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
MEMBRANE TRANSPORT
MEMBRANES
NUCLEI
NUCLEONS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC MEMBRANES
PIGMENTS
PROTEINS
PROTONS
RHODOPSIN
SCHIFF BASES
SPECTROPHOTOMETRY
STABLE ISOTOPES
TRACER TECHNIQUES