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The use of enzymes as valuable catalysts in organic solvents has been well documented. However, some of their features limit their application in organic synthesis, especially the frequently lower enzyme activity under nonaqueous conditions, which constitutes a major drawback in the application of enzymes in organic solvents. In addition, many enzymatic reactions are subject to substrate or product inhibition, leading to a decrease in the reaction rate and enantioselectivity. To overcome these drawbacks and to make enzymes more appealing to organic chemists, we demonstrate the use of cyclodextrins as regulators for the Pseudomonas cepacia lipase (PSL) and macrocyclic additives to enhance the reaction rate and enantioselectivity E in lipase-catalyzed enantioselective transesterification of 1-(2-furyl)ethanol in organic solvents. Both reaction rate and enantioselectivity were significantly enhanced by several orders of magnitude when using co-lyophilized lipase in the presence of cyclodextrins. The effect of cyclodextrin derivatives as well as solvents on the improvement of the reaction parameters has been studied. The observed enhancement was tentatively interpreted in terms of their ability to give a certain flexibility to the enzyme and to form a host–guest complex, thus avoiding product inhibition and leading to enhancement of the reaction rate and enantioselectivity. The effect of cyclodextrin additives on the enzyme morphology has been studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) of the co-lyophilized lipase with cyclodextrins. The ability of cyclodextrins to form a host–guest complex to avoid product inhibition, which leads to the observed enhancement, has been proved by NOESY, COSY, 13C and 1H NMR.

Item Type:	Refereed Article
Keywords:	enzyme, catalyst, organic solvent, cyclodextrins,
Research Division:	Chemical Sciences
Research Group:	Organic Chemistry
Research Field:	Organic Green Chemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Ghanem, A (Dr Ashraf Ghanem)
ID Code:	58302
Year Published:	2003
Web of Science® Times Cited:	41
Deposited By:	Austn Centre for Research in Separation Science
Deposited On:	2009-09-25
Last Modified:	2013-01-07
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