title: Positive charges of polyamines protect PSII in isolated thylakoid membranes during photoinhibitory conditions.
abstract: The effects of the positive charges of amines such as spermine (SPM), putrescine (PUT) and methylamine (MET) on the protection of PSII against excessive illumination were investigated in isolated thylakoid membranes. Under photoinhibition conditions, water oxidation, the kinetics of the Chl fluorescence rise and charge recombination in PSII were affected. A low concentration of SPM (1 mM) added before photoinhibition produced a significant improvement of F(v)/F(0), the oxygen yield and the amplitude of the B-band of thermoluminescence compared with the other amines. Amongst the amines studied, only SPM could protect the photosynthetic apparatus under photoinhibition conditions. This protection was probably provided by the polycationic nature of SPM (four positive charges at physiological pH), which can stabilize surface-exposed proteins of PSII through electrostatic interaction.
authors.affiliation: Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada G9A 5H7.
authors.forename: Saber
authors.initials: S
authors.lastname: Hamdani
authors.forename: Alain
authors.initials: A
authors.lastname: Gauthier
authors.forename: Najoua
authors.initials: N
authors.lastname: Msilini
authors.forename: Robert
authors.initials: R
authors.lastname: Carpentier
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D008027:Light; D049449:Luminescence; D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D011073:Polyamines / Q000378:metabolism*; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D018724:Spinacia oleracea / Q000378:metabolism* / Q000528:radiation effects*; D013696:Temperature; D020524:Thylakoids / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D045332:Photosystem II Protein Complex; D011073:Polyamines; D002734:Chlorophyll; D010100:Oxygen