Interplay between structure and fluidity of model lipid membranes under oxidative attack.
A proper regulation of membrane fluidity is critical for cellular activities such as communication between cells, mitosis, and endocytosis. Unsaturated lipids, a main component of biological membranes, are particularly susceptible to oxidative attack of reactive oxygen species. The oxidation of lipids can produce structural derangement of membranes and eventually alter the membrane fluidity. We have applied fluorescence correlation spectroscopy (FCS) and Raman spectroscopy to investigate the fluidity and structure of model membranes subject to oxidative attack. Hydrogen peroxide has little effect on the lateral fluidity of membranes, whereas hydroxyl radical causes a significantly increased fluidity. The latter is rationalized with the cleavage of the acyl chains of lipids caused by hydroxyl radical; this interpretation is founded on the diminished intensities of lines in Raman spectra associated with -CH(2) and C═C moieties in lipids and supported by mass-spectral measurements. The same approach provides a mechanistic account of the inhibitory capability of vitamins C and E against the increased membrane fluidity resulting from an oxidative attack. Membranes with much cholesterol exhibit a novel resistance against altered membrane fluidity induced with oxidative attack; this finding has biological implications. Our approach combining FCS and Raman measurements reveals the interplay between the structure and fluidity of membranes and provides insight into the pathophysiology of cellular oxidative injury.
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 300, Taiwan.
Wan-Yu
WY
Tai
Yi-Cyun
YC
Yang
Hui-Jen
HJ
Lin
Chin-Ping
CP
Huang
Yi-Lin
YL
Cheng
Mei-Fang
MF
Chen
Hsiu-Lan
HL
Yen
Ian
I
Liau
D001205:Ascorbic Acid / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D015227:Lipid Peroxidation; D008560:Membrane Fluidity; D010084:Oxidation-Reduction; D013050:Spectrometry, Fluorescence; D013059:Spectrum Analysis, Raman; D053835:Unilamellar Liposomes / Q000737:chemistry*; D014810:Vitamin E / Q000737:chemistry
D053835:Unilamellar Liposomes; D014810:Vitamin E; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid