Photoelectric response of purple membrane fragments adsorbed on a lipid monolayer supported by mercury and characterization of the resulting interphase.
Bioelectrochemistry
; 57(2): 155-66, 2002 Sep.
Article
em En
| MEDLINE
| ID: mdl-12160613
ABSTRACT
Purple membrane (PM) fragments were adsorbed on a dioleoylphosphatidylcholine (DOPC) monolayer supported by mercury to investigate the kinetics of light-driven proton transport by bacteriorhodopsin (bR). PM fragments were also adsorbed on a mercury-supported triethyleneoxythiol (TET) monolayer. On both monolayers, the light-on current exhibits a finite, potential dependent stationary component that decreases linearly with a positive shift in the applied potential. The light-on and light-off capacitive photocurrents were interpreted on the basis of a simple equivalent circuit, which accounts for the potential dependence of the stationary light-on current. The potential of zero stationary current is about equal to +0.010 V vs. saturated calomel electrode (SCE) on DOPC-coated mercury. The absolute potential difference across the PM fragments adsorbed at this applied potential was estimated on the basis of extrathermodynamic considerations and amounts to about +260 mV; it compares favorably with the value, +250 mV, of the transmembrane potential of zero stationary current across an oocyte plasma membrane incorporating bR [Biophys. J. 74 (1998) 403.]. The effect of the proton pumping activity of photoexcited PM fragments on the electroreduction kinetics of ubiquinone-10 incorporated in the DOPC monolayer underlying the PM fragments was investigated.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfatidilcolinas
/
Bacteriorodopsinas
/
Membrana Purpúrea
/
Membranas Artificiais
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Revista:
Bioelectrochemistry
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Itália