A study on the applicability of L-aspartate alpha-decarboxylase in the biobased production of nitrogen containing chemicals

beta-Alanine could serve as an intermediate in the biobased production of nitrogen containing chemicals from L-aspartic acid. Following the biorefinery concept, L-aspartic acid could become widely available from biomass waste streams via the nitrogen storage polypeptide cyanophycin. Since alpha-decarboxylation of L-aspartic acid is difficult to perform chemically, the applicability of Escherichia coli L-aspartate alpha-decarboxylase (EC 4.1.1.11) (ADC) for the production of beta-alanine was studied. With an increasing activity up to 90 degrees C and maintaining its activity upon storage for 24 hours at 60 degrees C, ADC showed a remarkably high thermostability. ADC has an optimum at pH 7.5 and starts to lose activity upon storage below pH 6. An inhibiting effect by beta-alanine was not observed. Immobilization on Sepabeads EC-EP and EC-HFA epoxy supports did not result in an increased thermostability, but did improve operational stability. Nonetheless, enzyme inactivation occurs during catalysis, probably caused by irreversible transamination of the catalytically essential pyruvoyl group.