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Overcoming the thermodynamic limitation in asymmetric hydrogen transfer reactions catalyzed by whole cells
Author(s) -
Goldberg Katja,
Edegger Klaus,
Kroutil Wolfgang,
Liese Andreas
Publication year - 2006
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.21014
Subject(s) - chemistry , catalysis , ketone , alcohol , acetone , cofactor , hydrogen , substrate (aquarium) , combinatorial chemistry , organic chemistry , enzyme , oceanography , geology
Whole lyophilized cells of an Escherichia coli overexpressing the alcohol dehydrogenase (ADH‐‘A’) from Rhodococcus ruber DSM 44541 were used for the asymmetric reduction of ketones to secondary alcohols. The recycling of the required nicotinamide cofactor (NADH) was achieved in a coupled‐substrate process. In the course of the reaction the ketone is reduced to the alcohol and the hydrogen donor 2‐propanol is oxidized to acetone by one enzyme. This leads to a thermodynamic equilibrium between all four components determining the maximum achievable conversion. To overcome this limitation an in situ product removal technique (ISPR) for the application with whole cells was developed. In this method the most volatile compound is separated from the reaction vessel by an air flow resulting in a shift of the equilibrium towards the desired secondary alcohol. The so‐called stripping process represents a simple and efficient method to overcome the thermodynamic limitation in biocatalytic reactions. Employing this method, the conversion of selected biotransformations was increased up to completeness. © 2006 Wiley Periodicals, Inc.