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Jonas, Ana Williams, Malcolm Irvin 2014-12-17T21:58:38Z 2014-12-17T21:58:38Z 10000-01-01 1988 1988 Discoidal-reconstructed high density lipoproteins (rHDL) were used to study the effect of HDL substrates on phosphatidylcholine (PC) transfer by human plasma phospholipid transfer protein (PLTP) by changing the composition and size of rHDL. Sonicated egg-PC:cholesterol vesicles containing radiolabelled dipalmitoyl-PC ($\sp $C-DPPC) were used as donors and varied rHDL, consisting of apolipoprotein, phospholipid and cholesterol, were used as acceptors. PLTP, purified about 3,400-fold, was used in the experiments. Activity was measured by the percent $\sp $C-DPPC transferred from vesicles into rHDL. There was no selectivity in facilitated $\sp $C-DPPC transfer at 5:1, PC molar ratio of vesicles/rHDL for the three major apolipoproteins of HDL; however, apolipoprotein (apo) AI-containing rHDL was more stable than apo AII and apo C-containing rHDL in the incubation system. Therefore, apo AI was used in subsequent experiments. When DPPC, egg-PC, palmitoyloleoyl-PC (POPC), dioleoyl-PC (DOPC), and dilinoleoyl-PC (DLPC) were incorporated into rHDL, the particle sizes and transfer activity decreased as follows: DPPC $>$ egg-PC $>$ POPC $>$ DOPC $\approx$ DLPC. The inclusion of varied amounts of cholesterol (0-30%)and sphingomyelin (0-100%) resulted in decreased transfer as these structural lipids increased. The effect of charge was studied by incorporating the anionic phospholipid, dipalmitoyl-phosphatidylserine (DPPS), 0-20%, and the cationic detergent, stearylamine, 0-20%. At low DPPS levels (0-5%), transfer was inhibited, whereas, at higher levels (10-20%), the transfer was higher than that seen at lower DPPS levels. Opposite effects were observed for stearylamine. From these results it is concluded that PC transfer appears to be sensitive to the morphology and changes in the interfacial properties of the acceptor particles--indicating that PLTP interacts with the rHDL acceptor. Fluidity is probably not a major factor. PLTP accelerates PC mass transfer from rHDL into native human LDL, leading to the formation of rHDL particles with a limiting diameter of 7.8 nm. Both the spontaneous and facilitated transfer rates increased with increasing concentrations of rHDL and LDL--suggesting participation of both particles in the transfer mechanism. The E$\sb{\rm a}$ values were similar for both the vesicle-rHDL and the rHDL-LDL systems. Made available in DSpace on 2014-12-17T21:58:38Z (GMT). No. of bitstreams: 1 8908891.pdf: 4566517 bytes, checksum: 507c736026f22b739863c2299040cf7e (MD5) Previous issue date: 1988 Embargo set by: Seth Robbins for item 72517 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 183 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988. http://hdl.handle.net/2142/72349 (UMI)AAI8908891 Chemistry, Biochemistry Health Sciences, Nutrition Effect of Structure and Composition of Reconstituted High Density Lipoproteins on Phosphatidylcholine Transfer by Human Plasma Phospholipid Transfer Protein text Biochemistry Biochemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.