Physics Colloquium: Perturbing bilayers: ceramide phosphorylation, lung-surfactant-protein palmitoylation, and pressure

Event Details

  • Speaker(s): Michael R. Morrow
  • Date:
  • Time: 10:30 a.m.
  • Location: MacN 222

BIG is co-sponsoring this lecture by Dr. Michael Morrow. All are welcome to attend.

ABSTRACT

One way to learn about the material properties of lipid bilayers and related structures is to observe how they respond to different perturbations. This talk will describe three recent studies in which ^2 H NMR was used to observe the response of phospholipid bilayers to varous perturbing effects. The first study compares C_16 -C1P/DPPC and C_16 -ceramide/DPPC mixtures. Ceramide is implicated in programmed cell death (apoptosis) while ceramide 1-phosphate (C1P) promotes cell division. Comparison of phase separation in these mixtures suggests that phosphorylation of ceramide to yield C -C1P inhibits separation of more ordered ceramide-enriched domains. This may provide a clue as to how these sphingolipids function as second messengers. The second study is focussed on a palmitoylated amphipilic polypeptide, SP-C, that contributes to the spreading and maintenance of surfactant layers at the air-water interface in lungs. The low orientational order of the SP-C palmitate chains may be relevant to its function. In the third study, it was found that bilayers of two lipids, DPPC and DPPG, differing in headgroup structure and charge display different propensities to interdigitate in response to applied hydrostatic pressure.

Michael R. Morrow, P.Phys.
Department of Physics and Physical Oceanography
Memorial University of Newfoundland