Towards an understanding of the biological activity of glycolipids: a physicochemical study

Jemmett, Philip N. (2018). Towards an understanding of the biological activity of glycolipids: a physicochemical study. University of Birmingham. Ph.D.

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Abstract

Monolayers composed of \(N\)-palmitoyl sphingomyelin (SM) or dipalmitoylphosphatidylcholine (DPPC) have been investigated at the air|water interface. Bilayers of these molecules have also been investigated at the Au(111)|water interface. Monolayer studies revealed differences in molecular area between the two molecules, despite identical headgroups, suggesting the sphingosine backbone of SM allows a more densely packed monolayer structure. Polarisation modulated infrared reflection-absorption spectroscopy studies of the corresponding bilayers revealed that the alkyl chain orientation is comparable in either layer at positive potential but changes at negative potential, concomitantly with changes in solvation. Bilayers of both molecules changed structure once the surface charge density measured with chronocoulometry became negative.

Surface pressure-area isotherms, X-ray reflectometry and grazing incidence X-ray diffraction were used to investigate monolayers of glycolipids and their mixtures with DPPC. Unusual monolayer structures were found for single-component glycolipid monolayers. Monolayers composed of DPPC or SM mixed with biologically-relevant glycolipids were also investigated using isotherms. Glycolipid structures were chosen to emulate the structural features of the biologically active and potential drug target \(N\)-cerotic α galactosylceramide. Evidence was found for a specific interaction between DPPC and \(N\)-palmitoyl α-galactosylceramide but not between DPPC and \(N\)-palmitoyl β-galactosylceramide. A specific interaction between either glycolipid and SM was not observed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):