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Properties of membranes derived from the total lipids extracted from the human lens cortex and nucleus. Biochim Biophys Acta 2013 Jun;1828(6):1432-40

Date

02/27/2013

Pubmed ID

23438364

Pubmed Central ID

PMC3633468

DOI

10.1016/j.bbamem.2013.02.006

Abstract

Human lens lipid membranes prepared using a rapid solvent exchange method from the total lipids extracted from the clear lens cortex and nucleus of 41- to 60-year-old donors were investigated using electron paramagnetic resonance spin-labeling. Profiles of the phospholipid alkyl-chain order, fluidity, oxygen transport parameter, and hydrophobicity were assessed across coexisting membrane domains. Membranes prepared from the lens cortex and nucleus were found to contain two distinct lipid environments, the bulk phospholipid-cholesterol domain and the cholesterol bilayer domain (CBD). The alkyl chains of phospholipids were strongly ordered at all depths, indicating that the amplitude of the wobbling motion of alkyl chains was small. However, profiles of the membrane fluidity, which explicitly contain time (expressed as the spin-lattice relaxation rate) and depend on the rotational motion of spin labels, show relatively high fluidity of alkyl chains close to the membrane center. Profiles of the oxygen transport parameter and hydrophobicity have a rectangular shape and also indicate a high fluidity and hydrophobicity of the membrane center. The amount of CBD was greater in nuclear membranes than in cortical membranes. The presence of the CBD in lens lipid membranes, which at 37°C showed a permeability coefficient for oxygen about 60% smaller than across a water layer of the same thickness, would be expected to raise the barrier for oxygen transport across the fiber cell membrane. Properties of human membranes are compared with those obtained for membranes made of lipids extracted from cortex and nucleus of porcine and bovine eye lenses.

Author List

Mainali L, Raguz M, O'Brien WJ, Subczynski WK

Author

Witold K. Subczynski PhD Professor in the Biophysics department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adult
Cell Membrane
Cell Membrane Permeability
Diffusion
Electron Spin Resonance Spectroscopy
Humans
Hydrophobic and Hydrophilic Interactions
Lens Cortex, Crystalline
Lens Nucleus, Crystalline
Liposomes
Membrane Fluidity
Membrane Lipids
Middle Aged
Molecular Structure
Oxygen
Phospholipids
Time Factors