Dynamics of fluorescent biological probes in solution phase processes

In the past decade the use of fluorescence based methods has flourished in many areas of science. Fluorescence is relevant to chemical, physical, and biological sciences as a tool of investigation, analysis, control and diagnosis. The recent advances in light sources, detectors, and compact fast electronics has prompted the advent of new technology in these areas.; The development and characterization of new fluorescent probes is needed. The ability to tailor probes for specific environments is important. Many potential in vivo applications exist with the introduction of fluorescent residues amenable to protein incorporation and biological systems.; This thesis is a study of fluorescent molecules in heterogeneous environments. The study focuses on understanding the factors that determine a fluorescent probes ability to interact with and report on its molecular environment. The probes are derivatives of the naturally occurring amino acid tryptophan and its non-natural analog 7-azatryptophan. We began by studying 7-azaindole and 7-azatryptophan in saturated solutions of aqueous adipic acid in an effort to detect the onset of crystallization. 7-Azatryptophan has a carboxylic functionality in common the adipic acid and may act as a site for aggregation enabling it to detect self-assembly of solutes preceding crystallization. We monitor the steady state and time resolved emission and rotational dynamics of the chromophores as a function adipic acid concentration to determine the ability of the probe to sense solute events. The comparison of concentration-dependent results reveal the probes unique interactions with solutes arising from their structural differences.; We use the information gained on the properties of the 7-azaindole chromophore in the adipic acid system and extend its use to the biological realm for the study of small peptides. 7-Azatryptophan was attached covalently to a series of valine oligomers and studied in water and in several aqueous micelle solutions to provide well defined heterogeneous environments. This study establishes that a balance exists between ionic and dispersion forces and mediates interactions with micelles. The study of probe micelle interactions was continued using several tryptophan and 7-azatryptophan derivatives. This work elucidated structural criteria for interaction with micelles and revealed that the subtle differences in the indole and 7-azaindole chromophores lead to measurably different interactions in these heterogeneous environments. The work in this thesis provides a knowledge base to aid in the application and interpretation of tryptophan and azatryptophan derivatives as probes of heterogeneous systems and peptide environments. (Abstract shortened by UMI.)...