Substratselektivität von Lipasen bei der Veresterung und Umesterung cis-trans-isomerer Fettsäuren und Fettsäureester

The aim of this doctoral thesis was the systematic determination of substrate selectivity of lipases towards unsaturated fatty acids and fatty acid esters with respect to position and configuration of C=C-double bonds. First, the substrate selectivity of 39 lipases from microorganisms, plants and animal tissue has been examined in the esterification of cis- and trans-9-octadecenoic acid (oleic and elaidic acid respectively) with n-butanol in n-hexane. While most of the lipases were unspecific towards the isomeric 9-octadecenoic acids, lipases from Candida cylindracea and Mucor miehei had a strong preference for the cis-9-isomer and catalysed the esterification of oleic acid 3-4 times faster than the reaction of elaidic acid. Only Candida antarctica lipase A favoured the trans-9-isomer as substrate and esterified elaidic acid 15 times faster than oleic acid. Examining the substrate selectivity in the esterification of linoleic (all-cis-9,12-octadecadienoic) acid, linolenic (all-cis-9,12,15-octadecatrienoic) acid and their all-trans-isomers with n-butanol in n-hexane as well as in the transesterification of cis/trans-isomeric 9,12-octadecadienoic acid methyl esters with n-butanol in n-hexane, once again lipases from Candida antarctica and Mucor miehei preferred fatty acids and fatty acid esters with a (first) cis double bond in delta-9-position, while the lipase A from Candida antarctica accepted trans-9-unsaturated substrates with high selectivity. Furthermore, lipases from Candida cylindracea and Mucor miehei as well as the lipase A from Candida antarctica has been used as biocatalysts in the esterification of the commercially available conjugated linoleic acid (CLA) isomers cis-9,trans-11-, cis-9,cis-11-, trans-9,trans-11- and trans-10,cis-12-octadecadienoic acid with n-butanol in n-hexane. As expexted, the cis-9-selective lipases from Candida cylindracea and Mucor miehei had a preference for the cis-9,trans-11-octadecadienoic acid, while the Candida antarctica lipase A favoured the trans-9, trans-11-isomer as substrate. Moreover, lipase from Candida cylindracea and lipase A from Candida antarctica were able to discriminate between cis-9,trans-11- and trans-10,cis-12-octadecadienoic acid. Therefore, these lipases has been used for the enzymatic fractionation of individual CLA-isomers, especially for the enrichment of the bioactive cis-9,trans-11-linoleic acid. Last but not least the substrate selecitvity of several microbial lipases towards cis/trans-isomeric octadecenoic acids and acid esters with C=C-double bond in the delta-6-, delta-7-, delta-8-, delta-10-, delta-11-, delta-12- and delta-13-position has been examined in the esterification and transesterification with n-butanol in n-hexane. Depending on the position of the C=C-double bond, lipases of Candida cylindracea and Mucor miehei preferred either the trans-isomer (even position: delta-6, delta-8, delta-10) or the cis-isomer (odd position: delta-7, delta-9, delta-11), while Candida antarctica lipase A always accepted the trans-isomer as substrate.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2005

Author dc:creator

• Borgdorf, Robert

Contributors dc:contributor

• Warwel, Siegfried

• info:eu-repo/classification/ddc/570
• Biowissenschaften, Biologie
• Lipase
• Substratselektivität
• Veresterung
• Fettsäuren
• cis/trans-Isomere
• substrate selectivity
• esterification
• fatty acids
• cis/trans-isomers

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123773%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62184