Stabilization of an amine transaminase for biocatalysis

• The previous loss of activity during storage is related to enzyme dimer dissociation.
• Enzyme stored for 6 months in 50% glycerol showed no loss of activity.
• The enzyme was co-lyophilized with surfactants for application in organic solvents.

The amine transaminase from Chromobacterium violaceum (Cv-ATA) is a well-known enzyme to achieve chiral amines of high enantiomeric excess in laboratory scales. However, the low operational stability of Cv-ATA limits the enzyme applicability on larger scales. In order to improve the operational stability of Cv-ATA, and thereby extending its applicability, factors (additives, co-solvents, organic solvents and different temperatures) targeting enzyme stability and activity were explored in order to find out how to store and apply the enzyme. The present investigation shows that the melting point of Cv-ATA is improved by adding sucrose or glycerol, separately. Further, by storing the enzyme at higher concentrations and in co-solvents, such as; 50% glycerol, 20% methanol or 10% DMSO, the active dimeric structure of Cv-ATA is retained. Enzyme stored in 50% glycerol at −20 °C was e.g., still fully active after 6 months. Finally, the enzyme performance was improved 5-fold by a co-lyophilization with surfactants prior to usage in isooctane.

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