Biophysical and bioanalytical studies of hyaluronan and lipids.

Hyaluron;Lipid;Vitreous;Nuclear magnetic resonance;NMR;Mass spectrometry;MS

Kristen Ann Magness, 1981-

University:University of Louisville

Department:Chemistry

关键词: Hyaluron;    Lipid;    Vitreous;    Nuclear magnetic resonance;    NMR;    Mass spectrometry;    MS;   

Others  :  https://ir.library.louisville.edu/cgi/viewcontent.cgi?article=1882&context=etd

美国|英语

来源: The Universite of Louisville's Institutional Repository

【 摘 要 】

Hyaluronan (HA) is a major structural component of the ocular vitreous humor(VH) and lipids are essential building blocks of cell membranes. However, little is knownabout their possible interactions. The VH is known to undergo liquefaction throughoutthe lifetime that may result in complications such as posterior vitreous detachment. Thepossible roles of lipids in the age-dependent liquefaction of the VH are unknown.As a first step in this new area of research in our group, model studies of therepeating unit of polymeric HA were performed. This unit contains glucuronate (GlcU)linked to N-acetylglucosamine (G1cNAc) via a 1-3 linkage. The sample contained both aand ß anomers leading to significant NMR (nuclear magnetic resonance) spectralcomplexity. Through the powerful combination of inverse heteronuclear 2D experiments,the resolution and assignment of all resonances for both anomers were achieved.Temperature-dependent changes in the NH resonances revealed the formation of weak or water-mediated intramolecular H-bonds. The polymeric form of HA was then investigated in D2O and its interactions with various lipids were probed.Theanalysisofchemicalshiftsandbandwidthsof1H NMRresonances revealedthestrongestinteractionstobebetweenHAandunsaturated oleic acid and lyso-oleoyl-phosphatidylcholine. Because matrix-assisted laser desorption/ionization mass spectrometry (MALDIMS) will be used toanalyze thecomponents of the VH in situ, weevaluated changes in relativeionization efficiencies(RIE)whentherepeatingunitof HAandlipidswere present in the model samples.Smaller lipid metabolites caused the greatest reduction of the RIE of HA but phosphatidic acid had no effect. On the other hand, HA decreased the ionization of all lipid species, almost equally, by ~50%. These findings suggest that the interactionsof thesespeciesinthegasphaselead topartialblockageof theionization sites.Preliminary results have been obtained for the VH by both NMR and MALDI-MS and do show the presence of lipids within the VH. In addition, oxidation of the VH leads to the presence of oxidized compounds and liquefaction. Future studies will focus on the isolation and characterization of these products of oxidation.