Permeability properties of large unilamellar vesicles of thylakoid lipids

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Plant Physiology, Supplement; (USA)

DOI:https://doi.org/10.1016/0005-2736(89)90340-4· OSTI ID:6648289

Webb, M S; Green, B R ^[1]

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1. Univ. of British Columbia, Vancouver (Canada)

The permeability properties of large unilamellar vesicles of chloroplast thylakoid lipid DGDG to {sup 86}Rb{sup +}, {sup 36}Cl{sup {minus}} and {sup 3}H-D- glucose have been determined. In addition, the permeabilities of binary, ternary, and quaternary mixtures of thylakoid lipids to {sup 86}Rb{sup +} have been measured. Vesicles of DGDG were found to be 60-130 fold more permeable to Rb{sup +} and 46-76 fold less permeable to Cl than PC vesicles. Vesicles of DGDG and PC were similar in glucose permeability. Electron spin resonance measurement of DGDG bilayer fluidity with the spin probes 5-doxyl-stearate and 12-doxy-stearate indicated that DGDG bilayers were not significantly more fluid than PC bilayers, indicating that fluidity differences could not account for the observed differences in ion permeability. The addition of 50 mol% of MGDG to DGDG vesicles had no effect on Rb{sup +} permeability, suggesting that the hexagonal-II phase preference of MGDG does not increase bilayer permeability. The addition of SQDG lead to a large increase in Rb{sup +} permeability. The calculated permeability coefficient to Rb{sup +} for a DGDG/MGDG/SQDG/PG (1/2/0.5/0.5) mixture similar to that of thylakoid membranes was 2.0-10{sup {minus}9} cm{center dot}s{sup {minus}1}. This value is three orders of magnitude higher than that for phospholipid systems, and ten-fold higher than that for vesicles of DGDG. It is proposed that the high permeability of thylakoid lipids to cations is the main cause of low observed thylakoid membrane electrical potentials and large proton gradients in chloroplasts.

• OSTI ID: 6648289
• Journal Information: Plant Physiology, Supplement; (USA), Journal Name: Plant Physiology, Supplement; (USA) Vol. 89:4; ISSN PPYSA; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
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Photobiological
& Thermochemical Conversion-- (1980-)
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59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
ALKALI METAL ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOPHYSICS
CARBOHYDRATES
CELL CONSTITUENTS
CELL MEMBRANES
CHLORINE 36
CHLORINE ISOTOPES
CHLOROPLASTS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON SPIN RESONANCE
GLUCOSE
HEXOSES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPIDS
LIPOSOMES
MAGNETIC RESONANCE
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
MINUTES LIVING RADIOISOTOPES
MONOSACCHARIDES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANOIDS
PERMEABILITY
PHOTOSYNTHETIC MEMBRANES
PROTEINS
RADIOISOTOPES
RESONANCE
RUBIDIUM 86
RUBIDIUM ISOTOPES
SACCHARIDES
THYLAKOID MEMBRANE PROTEINS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
YEARS LIVING RADIOISOTOPES