Enantioselective Esterification Of (±)-Menthol With Butyric Anhydride By Chemically Modified Candida Rugosa Lipase
Commercial lipase from Candida rugosa was chemically modified with the aim to improve its catalytic properties in organic solvents. The chemical modifiers, aldehydes and monomethoxy polyethylene glycols, were covalently linked to the lysine residues at the surface of the enzyme. Enzymatic enantio...
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| Formato: | Tese |
| Idioma: | English English |
| Publicado em: |
2003
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| Assuntos: | |
| Acesso em linha: | http://psasir.upm.edu.my/id/eprint/11622/1/FSAS_2003_10.pdf |
| Resumo: | Commercial lipase from Candida rugosa was chemically modified with the aim to
improve its catalytic properties in organic solvents. The chemical modifiers,
aldehydes and monomethoxy polyethylene glycols, were covalently linked to the
lysine residues at the surface of the enzyme. Enzymatic enantioselective
esterification of racemic menthol in organic solvents using butyric anhydride as
acylating agent was performed with the chemically modified lipases. Different
degrees of modification, organic solvents, reaction temperatures and water activity
were examined for the influence on the percent yield and enantioselective formation
of (-)-menthyl butyrate. The percent yield increased as the degree of modification
increased but decreased slightly for the highest degree of modification. Organic
solvents with log P values above 2.5 gave higher yield, however high
enantioselectivity was obtained in all the organic solvents tested. The
enantioselectivity towards (-)-menthol decreased considerably as the reaction
temperature was increased. Enzyme derivatives exhibited better activity and
enantioselectivity at high aw. The alkylated lipases showed higher thermal, solvent |
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