Cyclodextrins: A potential tool for studying the role of glycerolipids in photosynthetic membranes

Abstract

A novel cyclodextrin derivative, i.e., permethylated-alpha-cyclodextrin (PM-alpha-CD), was used for removing glycerolipids from spinach thylakoid membranes and investigating their role in photosynthetic activities. A three-step selective removal of each lipid class was observed in treated membranes. Up to a concentration of 4 mM, PM-alpha-CD (in the presence of 75 microg chlorophyll a+b/mL), PM-alpha-CD displayed a marked selectivity for anionic lipids [sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG)] in comparison with galactolipids. At this concentration, half of PG and SQDG were removed. Within this range of concentration, the volume response of treated thylakoids to variation of osmolarity, an indirect mean of verifying the structural integrity of the membrane, was not altered. Similarly, neither photosystem II (PSII) nor photosystem I (PSI) activity was affected. In contrast, the low-temperature fluorescence ratio F695/F740 drastically diminished from 1.45 to about 0.7, essentially due to the decrease of PSII fluorescence. The results derived from the fast fluorescence rise expressed in the form of a spider suggest that the fraction of inactivated (non-Q(A) reducing) reaction centers (RC) increases while the active (Q(A) reducing) RC remained intact. Raising the concentration of PM-alpha-CD from 4 to 7 mM resulted in a progressive but greater diminution of the galactolipid level than that of SQDG and PG. Within this concentration range, the integrity of the membrane was not altered, nor was either PSII or PSI activity, whereas the F695/F740 ratio decreased to about 0.45 as well as the fraction of inactivated RC. At concentrations above 7 mM of PM-alpha-CD, the integrity of the membrane was impaired, resulting in a decrease of both electron transport activities. At all concentrations, PM-alpha-CD did not show any selectivity toward either the acyl chains of the lipid molecules or the molecular species of PG. The results are discussed in terms of the role of glycerolipids in thylakoid membrane function and the relationship of the chemical structure of PM-alpha-CD and its lipid removal capacity.

Nonlinear Enhancement of Oxygen Evolution in Thylakoid Membranes: Modeling the Effect of Light Intensity and β-Cyclodextrin Concentration

“…In the past few years, the cyclodextrins were applied successfully to the study of the photosynthetic activity in the thylakoid membrane of plant chloroplasts. − It was shown that β-CD, a cyclodextrin containing seven d -glucose units, affects the spectroscopic characteristics and the electron transport properties of isolated thylakoid membranes. − In short, β-CD induces a red-shift from 681 to 683 nm in the absorption and second derivative spectra of the thylakoids 7 which is assigned to perturbations affecting the Q Y (0,0) electronic transition in the plane of the chlorophyll (Chl) a molecule (see refs and ). However, the molecular interactions underlying this spectral shift are still not completely understood.…”

Interaction of fluorescent phospholipids with cyclodextrins

“…CDs are also able to bind phospholipids (Ohtani et al, 1989;Puglisi et al, 1996;Rawyler and Siegenthaler, 1996;Fauvelle et al, 1997;Debouzy et al, 1998;Nishijo and Mizuno, 1998;Nishijo et al, 2000;Leventis and Silvius, 2001;Duchêne and Siegenthaler, 2002;Anderson et al, 2004;Giocondi et al, 2004;Hatzi et al, 2007;Piel et al, 2007;Kainu et al, 2010;Huang and London, 2013). This interaction has a different CD-specificity compared with that observed for sterols.…”