Binary mixtures of asymmetric phosphatidylcholines with one acyl chain twice as long as the other
High-resolution differential scanning calorimetry and /sup 31/P NMR spectroscopy have been used to study aqueous phosphatidylcholine (PC) dispersions prepared from colyophilized mixtures of C(10):C-(22)PC/C(22):C(12)PC of various molar ratios. These two lipid species are highly asymmetric but have a common structural feature; namely, one acyl chain in the fully extended conformation is about twice as long as the other. The experimental results support two conclusions: (1) These two component lipids are miscible in all proportions in both gel and liquid-crystalline states. This type of system behaves as a nearly ideal mixture. Its calorimetric parameters are those expected on the basis of the mole fraction weighted average of the corresponding parameters for the pure components. (2) The component lipids appear to self-assemble, at T < T/sub m/, into a mixed interdigitated bilayer in excess water. In a mixed interdigitated bilayer, the short acyl chain of one asymmetric phosphatidylcholine on one side of the bilayer leaflet is apposed with the short acyl chain of another lipid molecule on the other side of the bilayer leaflet, while the longer acyl chain from each of the two leaflets crosses the entire hydrocarbon width of the bilayer. The fundamental packing unit, as well as the dynamic unit describing the axial rotator motion about the bilayer normal for this mixed interdigitated bilayer, is thus a dimer, whereas the packing unit assigned for the noninterdigitated bilayer such as C(16):C(16)PC lamellae is a monomer.
- Research Organization:
- Univ. of Virginia School of Medicine, Charlottesville
- OSTI ID:
- 5876785
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:17; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Behavior of Bilayer Leaflets in Asymmetric Model Membranes: Atomistic Simulation Studies
Structural aspects of pressure effects on infrared spectra of mixed-chain phosphatidylcholine assemblies in D/sub 2/O
Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
AQUEOUS SOLUTIONS
CALORIMETRY
CHOLINE
DISPERSIONS
DRUGS
ESTERS
HYDROXY COMPOUNDS
ISOTOPES
LIGHT NUCLEI
LIPIDS
LIPOTROPIC FACTORS
MAGNETIC RESONANCE
MEMBRANES
MIXTURES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHASE STUDIES
PHOSPHOLIPIDS
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
QUATERNARY COMPOUNDS
RESONANCE
SOLUTIONS
STABLE ISOTOPES