title: Surface-charge related actions of polylysine on thylakoid membranes.
abstract: Polycation binding to the negatively charged surface of chloroplast thylakoid membranes is known to cause an inhibition of photosystem I activity. It also interferes with the cation-dependent rearrangement of chlorophyll proteins in the thylakoid membrane. It was shown that added anions prevented or reversed the inhibition of photosystem I by polylysine without decreasing its binding to the membranes. Anions also caused a change in the interaction of the chlorophyll proteins in polylysine-treated thylakoids as indicated by an increase in the relative fluorescence intensity from photosystem II. In both cases, the relative effectiveness of the anions tested depended on their valence; for example, the tetravalent species Fe(CN)4-(6) was effective at concentration at least 2 orders of magnitude lower than the divalent species SO2-(4). These results suggest that anions act by screening the positive charge of the polylysine-coated membrane surface. Measurements of the response of the anionic fluorescent probe 1-anilinonapthalene-8-sulfonate to an addition of anions to polylysine-treated thylakoids supported this contention. It was concluded that the action of polylysine on photosystem I and on the chlorophyll proteins is mediated by changes of the electrical properties of the thylakoid membrane and may not involve a direct binding of the polycation to the affected membrane proteins.
mesh_terms: D000838:Anions / Q000494:pharmacology; D001665:Binding Sites / Q000187:drug effects; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D004563:Electrochemistry; D004579:Electron Transport; D007887:Fabaceae; D008565:Membrane Proteins / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology*; D010777:Photochemistry; D010940:Plant Proteins / Q000502:physiology*; D010946:Plants, Medicinal; D010970:Plastocyanin / Q000502:physiology*; D011107:Polylysine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013499:Surface Properties
chemical_list: D000838:Anions; D008565:Membrane Proteins; D010455:Peptides; D010940:Plant Proteins; D011107:Polylysine; D010970:Plastocyanin