Effect of Lipid Phase Transition on Molecular Assembly and Structural Stability of Bacteriorhodopsin Reconstituted into Phosphatidylcholine Liposomes with Different Acyl-Chain Lengths

2010 ◽  
Vol 114 (47) ◽  
pp. 15706-15711 ◽  
Author(s):  
Yasunori Yokoyama ◽  
Lumi Negishi ◽  
Taku Kitoh ◽  
Masashi Sonoyama ◽  
Yasuo Asami ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Stability ◽  
Acyl Chain ◽  
Molecular Assembly ◽  
Lipid Phase ◽  
Lipid Phase Transition ◽  
Phosphatidylcholine Liposomes ◽  
Chain Lengths

Fatty acyl chain structure, orientational order, and the lipid phase transition in Acholeplasma laidlawii B membranes. A review of recent 19F nuclear magnetic resonance studies

1984 ◽  
Vol 62 (11) ◽  
pp. 1134-1150 ◽  
Author(s):  
P. M. Macdonald ◽  
B. D. Sykes ◽  
R. N. McElhaney
Keyword(s):  
Phase Transition ◽  
Fatty Acids ◽  
Nuclear Magnetic Resonance ◽  
Acyl Chain ◽  
Orientational Order ◽  
Membrane Lipid ◽  
Fatty Acyl ◽  
Fatty Acyl Chain ◽  
Lipid Phase ◽  
Lipid Phase Transition

The orientational order parameters of monofluoropalmitic acids biosynthetically incorporated into membranes of Acholeplasma laidlawii B in the presence of a large excess of a variety of structurally diverse fatty acids have been determined via 19F nuclear magnetic resonance (19F NMR) spectroscopy. It is demonstrated that these monofluoropalmitic acids are relatively nonperturbing membrane probes based upon physical (differential scanning calorimetry), biochemical (membrane lipid analysis), and biological (growth studies) criteria. 19F NMR is shown to convey the same qualitative and quantitative picture of membrane lipid order provided by 2H-NMR techniques and to be sensitive to the structural characteristics of the membrane fatty acyl chains, as well as to the lipid phase transition. Representatives of each naturally occurring class of fatty acyl chain structures, including straight-chain saturated, methyl-branched, monounsaturated, and alicyclic-ring-substituted fatty acids, were studied and the 19F-NMR order parameters were correlated with the lipid phase transitions (determined calorimetrically). The lipid phase transition was the prime determinant of overall orientational order regardless of fatty acid structure. Effects upon orientational order attributable to specific structural substituents were discernible, but were secondary to the effects of the lipid phase transition. In the gel state, relative overall order was directly proportional to the temperature of the particular lipid phase transition. Not only the overall order, but also the order profile across the membrane was sensitive to the presence of particular structural substituents. In particular, in the gel state specific fatty acyl structures demonstrated a characteristic disordering effect in the membrane order profile. These various observations can be merged to provide a unified picture of the manner in which fatty acyl chain chemistry modulates the physical state of membrane lipids.

scholarly journals Effects of Curcumin on Lipid Membranes: an EPR Spin-label Study

2020 ◽  
Vol 78 (2) ◽  
pp. 139-147
Author(s):  
Mariusz Duda ◽  
Kaja Cygan ◽  
Anna Wisniewska-Becker
Keyword(s):  
Phase Transition ◽  
Lipid Membranes ◽  
Acyl Chain ◽  
Protective Role ◽  
Lipid Phase ◽  
Therapeutic Effects ◽  
Structural Effects ◽  
Spectral Parameters ◽  
Paramagnetic Resonance ◽  
Lipid Order

Abstract Curcumin is a yellow–orange dye widely used as a spice, food coloring and food preservative. It also exhibits a broad range of therapeutic effects against different disorders such as cancer, diabetes, or neurodegenerative diseases. As a compound insoluble in water curcumin accumulates in cell membranes and due to this location it may indirectly lead to the observed effects by structurally altering the membrane environment. To exert strong structural effects on membrane curcumin needs to adopt a transbilayer orientation. However, there is no agreement in literature as to curcumin’s orientation and its structural effects on membranes. Here, we investigated the effects of curcumin on lipid order, lipid phase transition, and local polarity in a model liposome membranes made of DMPC or DSPC using electron paramagnetic resonance (EPR) spin labeling technique. Curcumin affected lipid order at different depths within the membrane: it slightly increased the phospholipid polar headgroup mobility as monitored by spectral parameters of T-PC, while along the acyl chain the ordering effect was observed in terms of order parameter S. Also, rotational correlation times τ2B and τ2C of 16-PC in the membrane center were increased by curcumin. Polarity measurements performed in frozen suspensions of liposomes revealed enhancement of water penetration by curcumin in the membrane center (16-PC) and in the polar headgroup region (T-PC) while the intermediate positions along the acyl chain (5-PC and 10-PC) were not significantly affected. Curcumin at a lower concentration (5 mol%) shifted the temperature of the DMPC main phase transition to lower values and increased the transition width, and at a higher concentration (10 mol%) abolished the transition completely. The observed effects suggest that curcumin adopts a transbilayer orientation within the membrane and most probably form oligomers of two molecules, each of them spanning the opposite bilayer leaflets. The effects are also discussed in terms of curcumin’s protective activity and compared with those imposed on membranes by other natural dyes known for their protective role, namely polar carotenoids, lutein and zeaxanthin.

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