Electric dipole moments of PS I-enriched membrane fragments

• Published in: Journal of photochemistry and photobiology. B, Biology Biology, 1997-05, Vol.39 (1), p.30-35
• Main Authors: Dobrikova, Anelia G., Busheva, Mira C., Taneva, Stefka G., Petkanchin, Ivana B.
• Format: Article
• Language: English
• Subjects: Electric light scattering; Electric polarizability; Permanent dipole moment; PS I-enriched particles; PS II-enriched particles
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/S1011-1344(96)00004-8

PS I-enriched fragments — 50 000 g and 129 000 g fractions, obtained by detergent treatment of pea chloroplasts — were studied by electric light scattering. This method gives the possibility both to determine the surface electric properties of the fragments and to distinguish between different polarization mechanisms. The applied electric fields in the range 0–100 kHz lead to an increase of the scattered light intensity, i.e. to a positive electro-optic effect α. The orientational behaviour of PS I fragments at low frequencies indicates that the contribution of permanent dipole moment in the alignment of the particles is negligible and that the orientation is induced by electric polarizability (along and perpendicular to the membrane surface: γ ∥ and γ s) Fragments enriched in photosystem I and photosystem II which are spatially separated in the appressed (grana) and non-appressed (stroma) membrane domains exhibit different mechanisms of interfacial polarization of the electric double layer.