Solubilization and localization of weakly polar lipids in unsonicated egg phosphatidylcholine: A sup 13 C MAS NMR study

Journal Article · Tue Mar 19 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00225a024· OSTI ID:5078425

Hamilton, J A ^[1]; Fujito, D T; Hammer, C F ^[2]

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1. Boston Univ. School of Medicine, MA (United States)
2. Georgetown Univ., Washington, DC (United States)

The weakly polar lipids cholesteryl ester, triacylglycerol, and diacylglycerol incorporate to a limited extent into the lamellar structure of small unilamellar vesicles. The localization of the carbonyl group(s) at the aqueous interface was detected by ({sup 13}C)carbonyl chemical shift changes relative to the neat unhydrated lipid. This study uses {sup 13}C NMR to investigate the interactions of thes lipids with unsonicated (multilamellar) phosphatidylcholine, a model system for cellular membranes and surfaces of emulsion particles with low curvature. Magic angle spinning reduced the broad lines of the unsonicated dispersions to narrow lines comparable to those from sonicated dispersions. ({sup 13}C)Carbonyl chemical shifts revealed incorporation of the three lipids into the lamellar structure of the unsonicated phospholipids and a partial hydration of the carbonyl groups similar to that observed in small vesicles. Other properties of interfacial weakly polar lipids in multilayers were similar to those in small unilamellar bilayers. There is thus a general tendency of weakly polar lipids to incorparate at least to a small extent into the lamellar structure of phospholipids and take on interfacial properties that are distinct from their bulk-phase properties. This pool of surface-located lipid is likely to be directly involved in enzymatyic transformations and protein-mediated transport. The {sup 13}C magic angle spinning NMR method may be generally useful for determining the orientation of molecules in model membranes.

• OSTI ID: 5078425
• Journal Information: Biochemistry; (United States), Vol. 30:11; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CELL MEMBRANES
BIOLOGICAL MODELS
PHOSPHOLIPIDS
NUCLEAR MAGNETIC RESONANCE
CARBON 13
CHEMICAL SHIFT
LIPIDS
MOLECULAR STRUCTURE
NMR SPECTRA
CARBON ISOTOPES
CELL CONSTITUENTS
ESTERS
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MEMBRANES
NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
RESONANCE
SPECTRA
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques