Phase separation in short-chain lecithin/gel-state long-chain lecithin aggregates

Journal Article · Tue Aug 28 04:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00486a022· OSTI ID:6101715

Bian, J; Roberts, M F ^[1]

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1. Boston College, Chestnut Hill, MA (USA)

Small bilayer particles for spontaneously from gel-state long-chain phospholipids such as dipalmitoylphosphatidylcholine and 0.2 mol fraction short-chain lecithins (e.g., diheptanoylphosphatidylcholine). When the particles are incubed at temperatures greater than the T{sub m} of the long-chain phosphatidylcholine (PC), the particles rapidly fuse (from 90-{angstrom} to {ge} 5,000-{angstrom} radius); this transition is reversible. A possible explanation for this behavior involves patching or phase separation of the short-chain component within the gel-state particle and randomization of both lipid species above T{sub m}. Differential scanning calorimetry, {sup 1}H T{sub 1} values of proteodiheptanoyl-PC in diheptanoyl-PC-d{sub 26}/dipalmitoyl-PC-d{sub 62} matrices of varying deuterium content, solid-state {sup 2}H NMR spectroscopy as a function of temperature, and fluorescence pyrene excimer-to-monomer ratios as a function of mole fraction diheptanoyl-PC provide evidence that such phase separation must occur. These results are used to construct a phase diagram for the diheptanoyl-PC/dipalmitoyl-PC system, to propose detailed geometric models for the different lipid particles involved, and to understand phospholipase kinetics toward the different aggregates.

• OSTI ID: 6101715
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:34; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
BARYONS
DEUTERIUM COMPOUNDS
DIAGRAMS
ELEMENTARY PARTICLES
EMISSION SPECTRA
EMISSION SPECTROSCOPY
ESTERS
FERMIONS
FLUORESCENCE SPECTROSCOPY
GEOMETRY
HADRONS
HYDROGEN COMPOUNDS
LECITHINS
LIPIDS
MAGNETIC RESONANCE
MATHEMATICS
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHASE DIAGRAMS
PHASE STUDIES
PHOSPHOLIPIDS
PROTONS
RELAXATION
RESONANCE
SPECTRA
SPECTROSCOPY
SPIN-LATTICE RELAXATION