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Effect of soluble and membrane proteins upon diethyl ether extraction of aqueous phospholipid dispersions
Author(s) -
ParentiCastelli G.,
Bertoli E.,
Sechi A. M.,
Silvestrini M. G.,
Lenaz G.
Publication year - 1974
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02532197
Subject(s) - chemistry , chromatography , phospholipid , diethyl ether , extraction (chemistry) , membrane , aqueous solution , ether , egg lecithin , lecithin , acetone , lipid bilayer , protein purification , biochemistry , organic chemistry
The effect of proteins upon diethyl ether extraction of phospholipids from aqueous dispersions has been investigated as a model for elucidating lipid‐protein interactions in the more complex membrane systems. Mixed phospholipids having a net anionic charge or purified lecithin (a zwitterion) are extracted from water dispersions into ether only after addition of salts. Basic proteins (lysozyme and cytochrome c ), by ionically binding phospholipids, allow extraction. Phospholipids are extracted together with the proteins in the form of neutralized lipid‐protein complexes. On the other hand, lipid depleted mitochondria (a hydrophobic protein residue after acetone extraction of mitochondria), after reconstitution with phospholipids, do not allow phospholipid extraction unless salts or basic proteins also are added to the system. This observation indicates that, in reconstituted membranes, the phospholipids are largely in the bilayer form with the polar heads still charged and susceptible to ether extraction only after neutralization with salts or basic proteins.