A nanoparticle-L-aspartate oxidase system for D-aspartate production

L-Aspartate oxidase (LASPO) performs the stereospecific oxidative deamination of L-aspartic acid to oxalacetate, ammonia and hydrogen peroxide [1]. LASPO from the thermophilic microorganism Solfolobus tokodaii (StLASPO) possesses very distinctive features that makes it very attractive for biotechnological applications: in particular, it can be used for the production of D-aspartate from a racemic mixture of D,L-aspartate, a molecule employed in the pharmaceutical industry, for parenteral nutrition, as food additive and in sweetener manufacturing [2]. Here, we present the StLASPO conjugation on iron oxide nanoparticles (NP-LASPO) using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and hydroxysuccinimide as cross-linking agents. This system presents a better pH and thermal stability than the free enzyme. Indeed, it was used for five times reaching the full L-aspartate conversion with an easy recovery after every cycle. The NP-LASPO system yielded a productivity in terms of L-aspartate conversion that is comparable to the one obtained with the free enzyme or with the enzyme immobilized on classical chromatographic supports. These results indicate that the NP-LASPO system has promising industrial applications [3]. This work is supported by Consorzio Interuniversitario per le Biotecnologie. I. A. is a student of the “Biotechnology, Biosciences and Surgical Technology” PhD course at Università degli studi dell’Insubria. References: 1. Tedeschi G et al., L-aspartate oxidase from Escherichia coli, European Journal of Biochemistry 1996; 239(2): 427-433. 2. Pollegioni L et al., L-Amino acid oxidase as biocatalyst: A dream too far?, Applied Microbiology and Biotechnology 2013; 97 (21): 9323–9341. 3. Armenia I et al., L-aspartate oxidase magnetic nanoparticles: synthesis, characterization and L-aspartate bioconversion, RSC Advances 2017; 7 (34): 21136-21143.