Lehrstuhl für Lebensmittelchemie
Am Hubland, 97074 Würzburg
Other participating persons and organisations:
Research foci (and basic equipment-based research projects):
Hydrolases and Oxidoreductases:
Enzymes such as lipases, glycosidases, oxygenases and chemically modified (semi-synthetic) enzymes such as e.g. seleno-subtilisin, as well as selected microorganisms are used as efficient and selective biocatalysts for the regioselective and stereoselective production of chemicals. Besides the chemically oriented work which is, in part, performed in collaboration with Prof. Dr. W. Adam's group (Organic Chemistry), increasing interest is focused on molecular-biological methodologies. In the latter field, fruitful cooperation exists with PD Dr. A. Schön (Biochemistry) to study alpha-dioxygenation in plants.
Serine in the active center of subtilisin Carlsberg and subtilisin BPN' was chemically converted to selenocysteine, resulting in the semisynthetic peroxidase seleno-subtilisin. It was used in free and immobilized form - each with high enantioselectivity - to study the kinetic resolution of hydroperoxides. The same objective was given for detailed studies using horseradish peroxidase. Extensive peroxidase investigations were also performed with Aspergillus ssp.. Lipoxygenase was employed for the regio- and enantioselective dioxygenation of 1,4-(Z,Z)-alkadienes and -trienes as well as arylalkenones such as curcumin. To produce optically active 2-hydroxy carboxylic acids, alpha-oxidase (from pea), glycolate oxidase (from spinach) and several lipases were used. Regioselective hydroxylation of alkanes was achieved with Bacillus megaterium. Stenotrophomonas maltophilia was successfully used for the production of 3-(R)-hydroxy fatty acids. Finally, the alpha-oxidase system from pea was characterized biochemically.
The instrumentation comprises among others HRGC, dynamic headspace-HRGC, HRGC-SCD, HRGC-MS, SPE-HRGC-MS, HRGC-IRMS, HPLC, HPLC-DAD, HPLC-ELSD, as well as HPLC-MS/MS and HPLC-NMR. For configurational studies MDGC, MDGC-MS and CD spectroscopy are well established. Quantifications are performed routinely by HRGC-MS and HPLC-MS/MS using preferably isotope dilution analysis