Journal article
Activity and stability of different immobilized preparations of recombinant E. coli cells containing ω-transaminase
Lund University, Department of Biotechnology, P.O. Box 124, 221 00 Lund, Sweden1
Cambrex Karlskoga AB, Björkborns industriområde, SE-691 85 Karlskoga, Sweden2
Production of chiral amines using ω-transaminases has been thoroughly studied in recent years. Immobilized ω-transaminases, however, have been used on relatively few occasions despite potential benefits such as reuse of enzyme and ease of product purification. In this study principally different methods including surface immobilization, entrapment and sweep flocculation using titanium oxide, Ca-alginate and chitosan respectively were evaluated for the immobilization of recombinant Escherichia coli cells.
The enzyme expressed was a modified Arthrobacter citreus ω-transaminase with improved thermostability. The preparations were compared in terms of cell loading capacity, operational stability in repeated batches and storage stability using the conversion of methylbenzylamine to acetophenone.The use of chitosan for cell immobilization proved to be the method of choice since it was both very simple and effective.
At a very high cell loading of 3.2g cells/g chitosan >60% activity was observed. The preparation was reused in eight successive 1-h batches with >90% remaining activity. To further demonstrate its usability the preparation was used for asymmetric synthesis of (S)-4′-cyano-(α)-methylbenzylamine in three repeated bathes (cycle time >20h), using isopropylamine as the amine donor.
Storage stability was comparable with that of non-immobilized cells. It was concluded that the chitosan method due to its properties and simplicity would be advantageous for use also on a larger scale.
Language: | English |
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Year: | 2012 |
ISSN: | 18733298 and 13595113 |
Types: | Journal article |
DOI: | 10.1016/j.procbio.2012.04.013 |