The outward component of photoinduced current in chloroplasts of Peperomia metallica.
The photoinduced currents in whole chloroplasts of Peperomia metallica were studied using suction electrodes and single-turnover flashes. The kinetic profile of the photocurrent contained a minor outward component (rise time, 100 micros). Local application (from the inside of the pipette) of a photosystem 2 inhibitor, DCMU, rapidly suppressed the outward current; conversely, addition of DCMU to the outer medium produced a transient stimulation of the outward component. Permeabilization of the tip-located membrane fragments with Triton X-100 eliminated the outward current, but had no significant influence on the inward current. The data suggest that the outward current originated in the tip-located nonruptured portions of the thylakoid membrane. Different involvement of two photosystems in the generation of the outward current indicates that granal thylakoids enriched with photosystem 2 are less susceptible to the rupture in the pipette tip as compared with stromal thylakoids.
Cherkashin
A A
AA
Lomonosov Moscow State University, Faculty of Biology, Russia. cherkashin@biophys.msu.ru
Bulychev
A A
AA
Vredenberg
W J
WJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002736:Chloroplasts / Q000502:physiology*; D004396:Coloring Agents / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D004237:Diuron / Q000494:pharmacology; D004735:Energy Transfer; D006096:Gramicidin / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology; D008027:Light; D008564:Membrane Potentials / Q000187:drug effects; D008773:Methylphenazonium Methosulfate / Q000494:pharmacology; D017830:Octoxynol / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010655:Phenylenediamines / Q000494:pharmacology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D026321:Piperaceae / Q000166:cytology / Q000502:physiology*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology
D000900:Anti-Bacterial Agents; D004396:Coloring Agents; D003902:Detergents; D006540:Herbicides; D010655:Phenylenediamines; D045322:Photosynthetic Reaction Center Complex Proteins; D006096:Gramicidin; D008773:Methylphenazonium Methosulfate; D017830:Octoxynol; D004237:Diuron; C029728:4-phenylenediamine