Experimental and Computational Studies in Bioorganic and Synthetic Organic Chemistry

Autor:	Lam, Polo Chun Hung
Rok vydání:	2004
Předmět:	Memory of Chirality Microtubules Dynamic Chirality Density Functional Theory Dynamic NMR Cation-Pi Interaction Amino Acids Asymmetric Synthesis PEG Taxol Paclitaxel Multivalent Binding Tryptophan
Druh dokumentu:	Dissertation
Popis:	Cationâ Ï interaction is an important determinant in protein structure and function. Among the three proteinogenic aromatic amino acids, tryptophan (Trp) is the strongest cationâ Ï donor. We reported the asymmetric syntheses of tryptophan regioisomers in which the amino acid side chain is attached at different position of the indole moiety. These new tryptophan regioisomers can effect a different mode of cationâ Ï interaction. In nature, dramatic increases in binding affinity can be achieved through multivalent binding. Following a fragmentation-dimerization approach, we synthesized Taxol-based dimer in which the baccatin III core of Taxol is coupled with flexible PEG linker. However, microtubule assembly assay suggested that these new dimers are not capable of effecting bivalent binding to the Taxol binding sites in microtubules. Memory of chirality (MOC) is an emerging theme in asymmetric synthesis in which the dynamic chirality of the reactive intermediate "memorizes" the static chirality of the reactant. Using dynamic 1D and 2D NMR and density functional theory (DFT) methods, we studied the MOC effect of 1,4-benzodiazepin-2-ones. Reconstruction of the reaction pathway using DFT calculations supported our proposed contra steric, retention of configuration mechanism. Ph. D.
Databáze:	Networked Digital Library of Theses & Dissertations
Externí odkaz:	http://hdl.handle.net/10919/40013 http://scholar.lib.vt.edu/theses/available/etd-10202004-130155/ Zobrazit plný text záznamu