Structural properties of a monobrominated analog of 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine

✍ Scribed by R.K. Lytz; J.C. Reinert; S.E. Church; H.H. Wickman

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 697 KB
• Volume: 35
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(84)90033-1

✦ Synopsis

Hydrated multibilayers of 1-palmitoyl-2-monobromopalmitoyl-sn-glyeero-3-phosphorylcholine (BrDPPC), where the 2-chain is brominated at either the C-9 or C-10 position, have been studied by low and wide angle X-ray diffraction methods. Oriented and unoriented samples were investigated. The long spacing was observed over the temperature interval -15°C to 80°C. A monotonic increase from approx. 50 A to approx. 62 A (28 wt. % H20) occurred with decreasing temperature. The BrDPPC showed no evidence of a sharp gel-toqiquid crystal phase transition. Wide angle scattering showed a diffuse peak corresponding to (4.5 A) -t. Differential scanning calorimetry measurements for hydrated liposomes (50 wt. % H~O) also showed no evidence for a phase transition (-40 < T < 60°C). These results suggest a low temperature amorphous (glass) state for the acyl side chains of BrDPPC. Monolayer film properties of monobrominated stearic acid also reflect a chain disordering effect occurring upon midchain substitution.