1. Selective facilitated transport of biological compounds through a phospholipid bilayer using boronic acid complexation. 2. Influence of eluent anions in boronate affinity chromatography. 3. Photoregulation of enzyme activity: Synthesis and study of ph

This dissertation encompasses three main topics: (1) the development of artificial and biological membrane transport systems for compounds which contain vicinal cis-diols, such as monosaccharides and nucleoside derivatives, (2) the development of new techniques in boronate affinity chromatography for the isolation of biological compounds at neutral pH, and (3) the development of photoswitchable enzyme inhibitors that can reversibly inhibit enzyme activity. Key to these subject matters is the use of reversible boronic acid complexation.;Boronic acids were found to facilitate the transport of monosaccharides and nucleosides in and out of liposomes. Boronic acids are the only artificial compounds that can selectively facilitate monosaccharide transport through bilayer membranes with the selectivity being sorbitol $>$ fructose $>$ glucose. Mechanistic studies indicate that the diol transport mechanism involves transient formation of a lipophilic, trigonal boronate ester. Further studies with E. coli showed that 5-fluorouridine has enhanced antibiotic activity in the presence of boronic acids.;New techniques in boronate affinity chromatography were developed for the isolation of biological compounds at neutral pH. Evidence showed that the eluent anions increased diol retention on commercially available boronate affinity columns by stabilizing the boronate-diol complexation. At pH 7.0, F$sp-$ ions enhanced ribonucleoside binding more effectively than any other anion examined. This finding has potential practical value as a simple method of increasing diol-specific binding while maintaining conditions close to physiological parameters, as well as providing insight into the mechanism of boronate-diol complexation.;The enzyme catalytic activities of chymotrypsin, subtilisin, and papain were found to be reversibly controlled with azobenzene transition-state-analogue inhibitors. Photomodulation of the shape of the inhibitor resulted in significant regulation of the inhibitory abilities. Attempts were made to immobilize a photoswitchable inhibitor to a solid support and use the matrix to extract enzymes from a solution in a reversible manner. Although initial results proved the technique to be problematic, there is still potential for its application in protein purification.