INVESTIGADORES
MARTINEZ Maria Alejandra
congresos y reuniones científicas
Título:
Screening for lipases performing chemo-enzymatic epoxidation
Autor/es:
TÖRNVALL, ULRIKA ; ADLERCREUTZ, DIETLIND ; MARTINEZ, M. ALEJANDRA; HATTI-KAUL, RAJNI
Lugar:
Venice
Reunión:
Simposio; Summer School on Green Chemistry 7th Edition. Venice, Italy; 2004
Institución organizadora:
CORDIS, the Community Research and Development Information Service
Resumen:
Screening for lipases
performing chemo-enzymatic epoxidation
ULRIKA TÖRNVALL, DIETLIND ADLERCREUTZ, ALEJANDRA
MARTINEZ, RAJNI
HATTI-KAUL
Department
of Biotechnology, Centre for Chemistry and Chemical Engineering, Lund
University, P.O. Box 124, SE-221 00 Lund, Sweden
Epoxidized
unsaturated fatty acids and their esters are valuable products for use as
building blocks in the synthesis of a vast amount of industrially important
products such as PVC-stabilizers, plasticizers, lubricating oils and as
additives to surface coatings. The industrial process for the manufacture of
these epoxides involves the use of a strong acid catalyst. The replacement of
this procedure by a chemo-enzymatic epoxidation using lipases is expected to
result in both a more environmentally benign and a more specific process. The
lipase catalyses the conversion of unsaturated fatty acids, in the presence of
hydrogen peroxide, to unsaturated peracids. The peracids subsequently undergo
spontaneous self-epoxidation. The stability of the enzyme towards the peroxide
and the peracids is an important parameter for an efficient process and
therefore methods for rapid screening of lipases exhibiting peroxidation
activity are being investigated.
We are using both
activity-based and gene-based approaches for screening of lipases suitable for
epoxidation reactions. Selectivity of the screening method is important for
obtaining lipase candidates with desired activity and stability features. The
activity-based method makes use of the ability of the lipase to generate
peracid from a fatty acid in the presence of hydrogen peroxide. The peracid
formed is then used for selective oxidation of the substance
2,2´-Azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) to its intensively
green radical cation. The ABTS assay has been used for screening of lipase
activity of a few commercial enzymes and isolates from extreme environments.
Commercially available immobilised lipases from Candida antarctica and Rhizomucor miehei have shown the highest
activity.
Based on this knowledge, lipases
related to C. antactica and R. miehei will be isolated and cloned
using the genome-sequence based approach. The use of PCR-fishing with highly
degenerated primers designed towards consensus regions of these lipases, such
as the oxy-anion hole and the active serine regions, will be used to search for
novel sequences from environmental isolates and samples. The results are
planned to be used for directed evolution, hopefully making it possible to
create an enzyme more stable against hydrogen peroxide and peracids.