%0 PDF %T MODIFICATION OF THE GANGLIOSIDE GM1 TO FACILITATE IMAGING AND FUNCTIONAL STUDIES. %A Liu, Zhao. %8 2017-04-18 %R http://localhost/files/pc289w982 %X Abstract: Since 1997, the lipid rafts model has been proposed to describe the structure and functions of cell membranes. Many efforts have been made to visualize the lipid rafts in living cells using various techniques, and revealed the lipid rafts have small size (20-200 nm) and short lifetime (<1 s). Nonetheless, the direct evidence remains lacking due to limitation of available techniques. We have designed a new detecting system using fluorinated ganglioside GM1 to probe lipid rafts by nanoSIMS imaging. We have synthesized a series of fluorinated ganglioside GM1 analogues (F-GM1s) by modification of natural GM1 that derived from bovine brain tissues using fluorinated fatty acid substitution on the lipid tails. (Chapter 2) Mono- and tri-fluorinated GM1 analogues have been obtained with fluorine atoms at different positions of the lipid tail. Higher order fluorination (-C6F13) of GM1 has also been accomplished either on the fatty acid chain or both the fatty acid (C6F13-GM1) and the sphingosine chains (Di-C6F13-GM1). This is the first report of modification of the sphingosine chain on ganglioside analogues. We have evaluated the biophysical properties of F-GM1s using multiple techniques, including FACS, AFM and calcium signaling assay. (Chapter 3) As a result, the terminal mono-fluorinated version (18-F-GM1) exhibited the highest similarity to the native GM1 and could be potentially used as a probe to study its behaviors in membranes. The mono-fluorinated GM1 analogues have been employed to study phase behaviors in a quaternary mixture of supported lipid bilayers using SIMS imaging. By isotopic labeling, domains rich in F-GM1 and cholesterol have been observed. Additionally, 18-F-GM1 formed larger domains than 12-F-GM1 in bilayers, which was attributed to their different phase transition temperature revealed by a DSC assay. We have designed and synthesized a NBD labeled GM1 analogue to study its endocytic pathway in cells. The GM1 analogue was incorporated in Hela cells and analyzed by confocal fluorescence microscopy. The fluorescently labeld GM1 was found accumulated in lysosomes, Golgi, and ER, thus provided a potential method for drug delivery and functional studies.; Thesis (Ph.D.)--Tufts University, 2012.; Submitted to the Dept. of Chemistry.; Advisor: Krishna Kumar.; Committee: Clay Bennett, Elena Rybak-Akimova, and Jianmin Gao.; Keywords: Chemistry, and Organic chemistry. %[ 2022-10-12 %9 Text %~ Tufts Digital Library %W Institution