Conformational catalysis of decarboxylation by host-guest interactions
The enzymatic decarboxylation reaction of N-carboxybiotin has been modeled by receptor-catalyzed decarboxylation of N-carboxyimidazolidinone. Factors that affect complex formation have been determined and the mechanism of decarboxylation was examined critically. A series of receptors have been synth...
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| Format: | Dissertation |
| Language: | English |
| Published: |
ProQuest Dissertations & Theses
01-01-1993
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| Online Access: | Get full text |
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| Summary: | The enzymatic decarboxylation reaction of N-carboxybiotin has been modeled by receptor-catalyzed decarboxylation of N-carboxyimidazolidinone. Factors that affect complex formation have been determined and the mechanism of decarboxylation was examined critically. A series of receptors have been synthesized and have shown to be suitable for complexation with imidazolidinone and derivatives. Factors that affect binding, for example, hydrogen bonding interactions, steric effects, aromatic overlaps, were examined. The receptor-catalyzed decarboxylation of N-carboxyimidazolidinone was studied and the catalytic rate constants were found to be of comparable magnitude to the enzymatic rates. The rate acceleration compared to the spontaneous decomposition of N-carboxyimidazolidinone in anhydrous tetrahydrofuran was more than 10$\sp6$. Rate acceleration was brought about by a decrease in activation barrier of the reaction. We propose that receptors provide a new route for reaction. Control experiments were performed which confirm the proposed mechanism of catalysis. |
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| ISBN: | 0315827513 9780315827516 |