The phosphoenolpyruvate-dependant carbohydrate transport system (PTS) couples uptake of a variety of carbohydrates with phosphorylation in prokaryotes. In this system, a phosphoryl group is sequentially transferred through two general phosphoryl carrier proteins, enzyme I (EI) and HPr, and a carbohydrate-specific permease enzyme II (EII). EII is constituted of two cytoplasmic domains IIA and IIB, and a transmembrane channel IIC domain. The galactitol-specific transporter (IIgat) belongs to the glucitol family and is structurally the least well-known. Nuclear Magnetic Resonance (NMR) spectroscopy was used to solve the three-dimensional structure of IIBGat. IIB Gat is composed of a central four-stranded parallel beta sheet flanked by alpha helices on both sides. NMR titrations and isothermal titration calorimetry (ITC) with IIAGat allowed the identification of the binding interface and preliminary modeling of the structure of the IIB Gat - IIAGat heterodimer. IIAGat was also phosphorylated in-vitro, producing several large chemical shift changes, but no changes to the overall structure.

A theoretical and experimental method is described whereby the hydrodynamic forces, both normal and shear, acting on the spheres of a doublet can be calculated. This is applied to a system of sphered human red blood cells agglutinated by human hyperimmune anti-B antiserum undergoing Poiseuille flow and observed using the traveling microtube technique. The mean forces separating the cells of individual doublets were found to be proportional to antiserum concentration from 0.73 to 3.56% v/v, normal forces increasing from 0.060 to 0.197 nN and shear forces from 0.023 to 0.072 nN. It was impossible to determine which force was responsible for break-up. Measurements of the doublets' mean dimensionless period of rotation indicated that doublets were rigidly linked. / Micropipet aspiration was applied to the same red cell-antibody system. Separation forces were $ sim2{1 over2}$ fold greater than for normal forces of the traveling microtube technique. Non-uniformity of red cell adhesiveness was also demonstrated.

This thesis studies optical microscopy based high order autocorrelation approaches for measuring molecular aggregation of fluorescently labeled particles in fluid systems. As the particles randomly diffuse into and out of the volume defined by the focus of a confocal laser beam illumination, the collected fluorescence intensity fluctuates. Fluorescence Correlation Spectroscopy (FCS) and Image Correlation Spectroscopy (ICS) have been used as methods which analyse temporal and spatial intensity fluctuations, and provide quantitative information of the molecular transport processes. Theoretical expressions for the high order autocorrelation function magnitudes for a non-interactive model are derived as well as their fitting equations for single- and multicomponent diffusion. / We present an experimental verification of the model applied to simple systems. Solutions of fluorescent microspheres of well-defined size have been imaged using confocal laser scanning microscopy. It has been shown that translational diffusion coefficients were not very sensitive to molecular size dispersion, which made a first order autocorrelation approach to be somewhat ineffective for dealing with multicomponent systems. We demonstrate that the number densities of a mixture of two fluorescent particles can be determined analyzing the higher order autocorrelation function magnitudes. Numerical simulations have been analyzed for testing the experimental tools we use. The technique outlined may be developed to detect and characterize aggregates of fluorescently labeled biological molecules such as membrane proteins and cell surface receptors. Such quantitative aggregation measurements, therefore, can provide information about the mechanism of intercellular signaling which is believed to depend on the oligomerization of cell membrane protein receptors.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 0833. Adviser: Paul R. Selvin. Includes bibliographical references (leaves 193-199) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7184. Adviser: Paul J. Hergenrother. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7184. Adviser: Klaus Schulten. Includes bibliographical references (leaves 125-137) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of California, San Francisco, 2005. / Source: Dissertation Abstracts International, Volume: 66-12, Section: B, page: 6479. Chair: R. Dyche Mullins.

Thesis (Ph. D.)--University OF MICHIGAN.

Thesis (Ph.D.)--University of California, San Francisco, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7181. Adviser: Brian K. Shoichet.

Thesis (Ph.D.)--University of California, San Francisco, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7183. Adviser: Daniel L. Minor, Jr.