Fourier transform infrared studies of immobilized and mobile artificial membranes
Abstract
Part I provides a practical understanding of how the infrared spectrometer generates infrared spectra and a functional understanding of the spectral data-manipulation technique Fourier deconvolution. Several examples of deconvolution are presented to illustrate a systematic approach to deconvolution. In addition, several deconvolution parameters are varied to indicate when these parameters are optimized. Part II describes the infrared microspectroscopic quantitation of functional groups coupled to chromatographic-silica surfaces. This rapid assay monitored the stability of the novel HPLC chromatographic bonded phase Immobilized Artificial Membranes (IAM) which contain phospholipid molecules immobilized to silica. This non-sample-destructive technique quantitated and characterized IAM lipid-silica matrices that were challenged with mobile phase solvents alone and with deoxynucleotide analytes. The assay quantitated immobilized lipid functional groups by correlating the ratio of the band area of interest to the silica oxide combination band area. This technique also identified adsorbed mobile phase buffer components which influenced the IAM chromatography of deoxynucleotides. Part III describes phosphate headgroup conformational changes in dilauroylphosphatidylcholine (diC$\sb{12}$PC) bilayers, with and without fatty-acid-amino-acids guest molecules, as monitored by RO-P-OR single bond vibrations. Formation of the antiplanar-antiplanar (ap-ap) phosphodiester conformation was observed in pure diC$\sb{12}$PC bilayers formed at 5$\sp\circ$C and in diC$\sb{12}$PC/fatty acid-amino-acid mixed bilayers formed under all conditions. The extent of ap-ap phosphodiester formation depended on the bilayer formation conditions (i.e., temperature, pre-incubation time and D$\sb2$O solvent). Upon the formation of the ap-ap phosphodiester conformation, no changes in hydration of either the phosphate group or the carbonyl ester group were detected and in addition, no trans/gauche conformational changes in the acyl chains were observed. Part IV describes a useful infrared technique which quantitates the lipid content in extracted membrane preparations. Infrared analysis of thin films of lipid extract on CaF$\sb2$ containing perdeuterated nanodecane as an internal standard permitted lipid quantitation with $>$98% accuracy.
Degree
Ph.D.
Advisors
Pidgeon, Purdue University.
Subject Area
Pharmacology|Analytical chemistry|Biochemistry
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