Title

Study of the functional peptides and peptidolipids in two dimensions: A surface chemistry approach

Date of Award

2005

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Chemistry

First Committee Member

Roger M. Leblanc, Committee Chair

Abstract

Primarily, this dissertation describes a unique 2D approach that has novel film architecture by controlling a balance of hydrogen-bonding and van der Waals forces. The study suggests that the highly correlated physical parameters are useful to develop new film architecture.Polymerization of a cysteinyl peptidolipid Langmuir film at the air-water interface is presented. Intermolecular disulfide bonds of the peptidolipid formation of sulfhydryl groups were triggered by oxygen flushed in the water subphase in slightly alkaline condition. The epi-fluorescence and ESEM microscopies were used to study the topography of the polymers formed in either Langmuir or LB films. Increased stability and rigidity of the Langmuir film formed by the cysteinyl peptidolipid could possibly broaden its applications in sensors, biomembranes and other areas.Next, this dissertation will enrich knowledge of the neuritic plaques formed by amyloid beta peptide (Abeta); Abeta plays a seminal role in the pathogenesis of Alzheimer's disease (AD). Abeta sequence 31--35 (IIGLM) and 25--35 (GSNKGAIIGLM) are among the most frequently studied Abeta derivatives. These fragments possess the structural characteristic of Abeta and retain its neurotoxicity. We apply the two dimensional (2D) approach to investigate the aggregation of these fragments. To improve their stability and self-assembly at the air-water interface, the fragments were modified with an aliphatic chain at the N-terminus of the peptide's carboxylic acid or amide moieties. Surface chemistry techniques were applied to monitor the aggregation process and the real time epi-fluorescence microscopy was utilized to observe the topography of the domains formed, whereas IRRAS provided the information on the spectral features of the domains at the air-water interface. Supplementary spectroscopic techniques including MAIR, RA, CD and ATR-FTIR were used to investigate the conformation of the domains in the LB film. Finally, aggregates formed with Abeta (31--35) and Abeta (1--42) were labeled using luminescent CdSe/ZnS Quantum Dots, this renders a higher intensity and better contrast for imaging the aggregates. This study aims to assist in the elucidation of the aggregation mechanism, potentially aiding the discovery of an effective cure for AD.

Keywords

Chemistry, Physical

Link to Full Text

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