Abstract
Human serum lipoproteins and egg yolk lecithin liposomes are able to solubilize large amounts of n-hexane and n-octane. At the maximum water solubility of n-octane the mole ratio of alkane to lipoprotein was 65 for high density lipoprotein (holo-HDL) and 900 for low density lipoprotein (holo-LDL). Alkane binding to lipid-free apo-HDL is negligible compared to alkane solubility in holo-HDL. Alkane solubility in the lipoproteins and liposomes is thermodynamically consistent with the simple soution of hydrocarbon in the hydrophobic regions of these particles. The unitary free energies of alkane transfer are similar to values previously observed for detergent micelles but are less favorable by 0.8 kcal/mol from the free energy of transfer to liquid hydrocarbon. It is concluded that the thermodynamics of alkane transfer to the lipoproteins resembles that found for detergent micelles or liposomes rather than that anticipated for an "oil drop" (i.e. liquid hydrocarbon).
Highlights
Despite their importance in lipid transport and possible role octane
It is concluded that the thermodynamics of alkane holo-LDL small angle x-ray scattering diagrams suggest a single transfer to the lipoproteins resembles that found for deter- lipid phase in the form of a spherical lipid bilayer [9]
The threegent micelles or liposomes rather than that anticipated for component phase diagram in which cholesterol, cholesteryl an “oil drop”
Summary
Liposomes and Lipoproteins the interior hydrophobic sites of fl-lactoglobulin, myoglobin, and hemoglobin which are characterized by a free energy of alkane transfer, pro - nLwo, more negative than &C - nw”. This effect (Received for publication, February 3,1975) is due to a more favorable enthalpy of transfer to the protein and WILLIAM L. Duke University 27710 has been attributed to suboptimal interactions in the unoccupied hydrophobic sites [2]. Stone and Reynolds have recently described a fourth type of hydrophobic region for apo-Gin-I, the lipid-free major polypeptide component of human high density
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