The chemistry of unsaturated pyranosides and L-(–)-sucrose
Abstract
The stereoselective epoxidation of several unsaturated pyranosides (glycals and 4-deoxypentenosides) has been investigated using DMDO at low temperature. The stereochemical outcomes have been compared with theoretical analyses based on PPFMO theory, which appears to be an appropriate model for describing native electronic bias in the π bond. These results, in conjunction with ongoing studies of other unsaturated pyranosides, are expected to provide a comprehensive perspective on the structural factors which influence polarization bias in π-reactivity. L-(–)-sucrose was stereoselectively synthesized using an intramolecular aglycone delivery protocol, and was used to elucidate the presence of a significant osmotic pressure effect on the substrate inhibition of the enzyme invertase, which catalyzes the hydrolysis of the disaccharide D-(+)-sucrose. The osmotic effect was evaluated by adding various amounts of L-(–)-sucrose to solutions of invertase containing a constant concentration of D-(+)-sucrose, corresponding to the peak enzymatic activity. The relative decrease in invertase activity at the highest D/L-sucrose concentrations used (0.5 M) was more than 30% of the activity loss ascribed otherwise to substrate inhibition. This study demonstrates that mirror-image molecules can be used to deconvolute nonspecific effects from true substrate inhibition.
Degree
Ph.D.
Advisors
Wei, Purdue University.
Subject Area
Organic chemistry
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