Melittin-induced changes in thylakoid membranes: particle electrophoresis and light scattering study.
Thylakoids were used as a model system to evaluate the effect of bee venom peptide melittin (Mt) on membrane surface charge. At neutral pH, thylakoid membrane surfaces carry excess negative electrical charge. Mt strongly altered the electrophoretic mobility (EPM) of 'low-salt' thylakoids and did not significantly change the EPM of 'high-salt' thylakoids. Mt increased the primary ionic-exchange processes across the 'low-salt' thylakoid membranes, while it did not affect those of 'high-salt' thylakoids. Mt decreased the proton gradient generation on the membranes at both ionic strengths, but it affected more strongly the 'high-salt' than that of 'low-salt' thylakoids. The primary photochemical activity of photosystem II, estimated by the ratio Fv/Fm, was not influenced by the low Mt concentrations. It decreased only when chloroplasts had been incubated with higher Mt concentrations and this effect was better expressed in 'low-salt' than in 'high-salt' thylakoid membranes.
Doltchinkova
Virjinia
V
Faculty of Biology, Department of Biophysics and Radiobiology, Sofia University, 8 Dragan Tzankov Boulevard, 1164 Sofia, Bulgaria. virjird@biofac.uni-sofia.bg
Georgieva
Katya
K
Traytcheva
Nelly
N
Slavov
Chavdar
C
Mishev
Kiril
K
D002734:Chlorophyll / Q000032:analysis; D002736:Chloroplasts / Q000187:drug effects* / Q000378:metabolism; D004586:Electrophoresis / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008555:Melitten / Q000737:chemistry / Q000494:pharmacology*; D009994:Osmolar Concentration; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000737:chemistry / Q000494:pharmacology*; D020524:Thylakoids / Q000187:drug effects* / Q000378:metabolism
D013501:Surface-Active Agents; D002734:Chlorophyll; D008555:Melitten