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Green Chem., 2009, 11, 1646 - 1652, DOI: 10.1039/b902731a

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

Paul M. Könst, Maurice C. R. Franssen, Elinor L. Scott and Johan P. M. Sanders

-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 -decarboxylation of L-aspartic acid is difficult to perform chemically, the applicability of Escherichia coliL-aspartate -decarboxylase (EC 4.1.1.11) (ADC) for the production of -alanine was studied. With an increasing activity up to 90 °C and maintaining its activity upon storage for 24 hours at 60 °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 -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.

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