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oai:www.ideals.illinois.edu:2142/19445 2023-07-10 col_2142_5131 col_2142_14795 com_2142_5130 com_2142_14794 com_2142_14793 com_2142_8903

Jonas, Ana Hefele Wald, Jennifer Elaine 2011-05-07T12:07:47Z 2011-05-07T12:07:47Z 10000-01-01 1990 High density lipoprotein (HDL) is believed to be involved in reverse cholesterol transport. HDL consists primarily of phospholipids, cholesterol, cholesterol esters, and apolipoprotein A-I (apo A-I). However, HDL is extremely heterogeneous in size composition and the structure of its lipoprotein components, particularly apo A-I. Due to its inherent structural heterogeneity, structure-function studies on native HDL have been extremely difficult. Techniques were thus developed to reconstitute HDL (rHDL) from apolipoproteins and pure lipids. These rHDL have been heterogeneous in size and the number of apo A-I molecules per complex. This work shows the isolation of 5 rHDL complexes to homogeneity, and the results of studies of rHDL, apo A-I, and lipid structure in these rHDL. Furthermore, the reactivity of these complexes with lecithin cholesterol acyltransferase (LCAT) was also investigated. The rHDL structures were investigated by assays for chemical composition; and the dimensions were determined by native gel electrophoresis and electron microscopy. The protein structure was studied by a variety of fluorescence techniques, and circular dichroism, and infrared spectroscopies. Monoclonal antibody studies, trypsinolysis and structural algorithmic studies were also employed to probe the protein structure. The lipid structure was studied by infrared spectroscopy, and with lipophilic fluorescent probes. Kinetic studies of the complexes were performed with LCAT. This work shows that apo A-I not only has a different structure in the lipid bound versus the lipid free state, but that it has distinct and reproducible structures in the lipid bound state. The alpha helices of apo A-I run parallel to the lipid acyl chains in the discoidal rHDL. The lipid dynamics are affected by both the lipid and protein composition of the complexes; and, differences in rHDL reactivity with LCAT are correlated to differences in lipid content, and apo A-I and rHDL structure. Made available in DSpace on 2011-05-07T12:07:47Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9114262.pdf: 7451839 bytes, checksum: 197266d5b6265fc9704baca988942387 (MD5) Previous issue date: 1990 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:37:00Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:15:08-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9114262 (UMI)AAI9114262 http://hdl.handle.net/2142/19445 eng Copyright 1990 Hefele Wald, Jennifer Elaine Chemistry, Biochemistry Health Sciences, Medicine and Surgery Structure and function studies on five homogeneous reconstituted HDL complexes text Biochemistry Biochemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.