Platelet-activating factor assemblies in excess water
High-sensitivity differential scanning calorimetric, vibrational Raman, and /sup 31/P NMR spectroscopic experiments have been performed as a function of temperature on aqueous dispersions of 1-0-octadeyl-2-acetoyl-sn-glycero-3-phosphocholine, a chemically synthesized platelet-activating factor. In the temperature range of -7 to 30/sup 0/C, the C(18):PAF-H/sub 2/O system is shown by Raman spectroscopy in the C-H stretching mode region to undergo two thermal phase transitions centered at 9.2 and 18.4/sup 0/C. However, an additional transition at 17.6/sup 0/C is observed by DSC, which can be assigned as the pretransition, or gel (I) ..-->.. gel (I') transition. The low temperature transition, attributed to the interdigitated lamellar gel (II) ..-->.. gel (I) phase transition is characterized by the breakdown of large interdigitated lamellar organizations into small, but aggregated, bilayer vesicles. The high-temperature transition corresponds to the interdigitated lamellar gel (I') ..-->.. micellar transition. The molecular ordering and packing structure of C(18):PAF in the various lamellar phases and phase transition regions will be discussed. It appears that the interdigitated lamellar gel (I) phase is unique for C(18):PAF dispersions when compared to the behavior of other chemically closely related phospholipids in excess water.
- Research Organization:
- Univ. of Virginia School of Medicine, Charlottesville
- OSTI ID:
- 5333696
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550600 -- Medicine
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
AQUEOUS SOLUTIONS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
CHOLINE
COAGULANTS
DISPERSIONS
DRUGS
HEMATOLOGIC AGENTS
HYDROXY COMPOUNDS
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MATERIALS
MIXTURES
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
QUATERNARY COMPOUNDS
RAMAN SPECTRA
SOLUTIONS
SPECTRA
STABLE ISOTOPES
TEMPERATURE DEPENDENCE