Abstract:
:The self assembly of phospholipid molecules in the bilayer form was considered in terms of equivalent molecular shapes representing intermolecular forces. The equivalent size of each phospholipid headgroup was approximated by the net atomic volume plus the volume of the associated water molecules, which was derived from water/hydrocarbon partitioning experiments. The equivalent lengths of unsaturated acyl chains were derived from the retention time data from chromatographic measurements. The spontaneous curvature of various phospholipid monolayers was calculated from their equivalent molecular shapes, and the energy required to flatten them to the bilayer plane was calculated, using the known bending modulus. With increasing bending energy, the mixtures showed increasing susceptibility to phospholipase A2, facilitated lipid transfer rate by phospholipid exchange proteins, permeability to carboxyfluorescein, incorporation of human erythrocyte proteins, and calcium transport by Ca-ATPase from sarcoplasmic reticulum in reconstituted vesicles. When the calculation was applied to known lipid compositions of nine cellular membranes, the protein/lipid ratio and phospholipid/cholesterol ratio were found to have a positive and a negative correlation, respectively, with the latent bending energy of the phospholipids. The energy expense in conforming to a bilayer phase may be an important physical parameter regarding the activity and the biogenesis of membranes.
journal_name
Proc Natl Acad Sci U S Aauthors
Hui SW,Sen Adoi
10.1073/pnas.86.15.5825subject
Has Abstractpub_date
1989-08-01 00:00:00pages
5825-9issue
15eissn
0027-8424issn
1091-6490journal_volume
86pub_type
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