Synthesis of a Photocleavable Bolalipid for the study of the roles of Phospholipid Transfer Proteins and Phosphatidylinositol Lipid Kinases

Abstract

This thesis was dedicated to the synthesis of mono- and di-photocleavable phosphatidylcholine bolalipids that were designed to investigate the mechanism of action of the phospholipid transfer protein, Sec14, as well as the phosphatidylinositol 4-kinase, Pik1. While it was the goal of this thesis to synthesize both bola-PCs, only the mono-photocleavable bola-PC was successfully synthesized. The mono-photocleavable bola-PC lipid was designed to contain two glycerol molecules that each had a choline head group connected through a phosphodiester bond at the sn3 position. Each glycerol was acylated with palmitic acid at the sn1 position. These two glycerol moieties were then connected to one another through their respective sn2 hydroxyls via a mono-photocleavable dicarboxylic acid. The initial steps of this work were to synthesize mono- and di-photocleavable diacids to serve as a linker for the polar head groups of the bolalipids. The mono- and di-photocleavable diacids were designed to contain one and two nitrophenyl ethyl photolabile protecting groups, respectively. The synthesis of the di-photocleavable diacid was attempted first, however, these efforts were unsuccessful. Two separate synthetic routes were followed to synthesize this diacid, but neither were viable. Despite this, the synthesis of the mono-photocleavable diacid was successful and was incorporated into a bola-PC. The mono-photocleavable diacid and bola-PC were found to undergo photocleavage when irradiated with 365 nm light, in 60 seconds and 105 seconds, respectively. Photocleavage of the bola-PC was also carried out within a lipid vesicle comprised of 10% bola-PC and 90% DOPC. Spectral and experimental data have been provided for all compounds synthesized. Future efforts will involve the bola-PC synthesized in this thesis undergoing enzymatic conversion into a bola-PI, via the enzyme phospholipase D.