ISSN:
0006-3592
Keywords:
enzyme
;
supercritical CO2
;
stability
;
effect of water
;
comparison with organic solvent
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
This study compares two solvents for enzymatic reactions: supercritical carbon dioxide (SCCO2) and organic solvent (n-hexane). The model reaction that was chosen was the esterification of oleic acid by ethanol catalyzed by an immobilized lipase from Mucor miehei (Lypozyme). The stability of the enzyme appeared to be quite good and similar in both media but was affected by the water content. Partition of water between solvents and immobilized enzyme has been calculated from experimental adsorption isotherms. The water content of the solid phase has a dramatic influence on the activity of the enzyme and its optimum value for activity was about 10% (w/w) in both media. A kinetic study enabled a Ping-Pong Bi-Bi reaction mechanism with inhibition by ethanol to be suggested. Despite some differences in kinetic constants, activity was in the same range in both media. Hypotheses for explaining the kinetic constant variations have been proposed and particular attention has been paid to the pH effects.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260390304
