Influence of molecular packing and phospholipid type on rates of cholesterol exchange

Journal Article · Tue May 03 04:00:00 EDT 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00409a044· OSTI ID:7253210

Lund-Katz, S; Laboda, H M; McLean, L R; Phillips, M C

The rates of (/sup 14/C)cholesterol transfer from small unilamellar vesicles containing cholesterol dissolved in bilayers of different phospholipids have been determined to examine the influence of phospholipid-cholesterol interactions on the rate of cholesterol desorption from the lipid-water interface. At 37/sup 0/C, for vesicles containing 10 mol % cholesterol, the half-times for exchange are about 1, 13, and 80 h, respectively, for unsaturated PC, saturated PC, and SM. In order to probe how differences in molecular packing in the bilayers cause the rate constants for cholesterol desorption to be in the order unsaturated PC > saturated PC > SM, nuclear magnetic resonance (NMR) and monolayer methods were used to evaluate the cholesterol physical state and interactions with phospholipid. The NMR relaxation parameters for (4-/sup 13/C) cholesterol reveal no differences in molecular dynamics in the above bilayers. The greater van der Waals interaction in the SM monolayer (or bilayer) compared to PC gives rise to a larger condensation by cholesterol. This is a direct demonstration of the greater interaction of cholesterol with SM compared to PC. An estimate of the van der Waals interactions between cholesterol and these phospholipids has been used to derive a relationship between the ratio of the rate constants for cholesterol desorption and the relative molecular areas (lateral packing density) in two bilayers. This analysis suggests that differences in cholesterol-phospholipid van der Waals interaction energy are an important cause of varying rates of cholesterol exchange from different host phospholipid bilayers.

• Research Organization: Medical College of Pennsylvania, Philadelphia (USA)
• OSTI ID: 7253210
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:9; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
BIOCHEMISTRY
CARBON 13
CARBON 14 COMPOUNDS
CARBON ISOTOPES
CHEMISTRY
CHOLESTEROL
ESTERS
EVEN-ODD NUCLEI
HYDROXY COMPOUNDS
ISOTHERMS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MEMBRANE TRANSPORT
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
RESONANCE
STABLE ISOTOPES
STEROIDS
STEROLS