Abstract

Arginyl dipeptides like Arg-Ser, Arg-Ala, and Arg-Gly are salt-taste enhancers and can potentially be used to reduce the salt content of food. The l-amino acid ligase RizA from B. subtilis selectively synthesizes arginyl dipeptides. However, industrial application is prevented by the high cost of the cofactor adenosine triphosphate (ATP). Thus, a coupled reaction system was created consisting of RizA and acetate kinase (AckA) from E. coli providing ATP regeneration from acetyl phosphate. Both enzymes were recombinantly produced in E. coli and purified by affinity chromatography. Biocatalytic reactions were varied and analyzed by RP-HPLC with fluorescence detection. Under optimal conditions the system produced up to 5.9 g/L Arg-Ser corresponding to an ATP efficiency of 23 g Arg-Ser per gram ATP. Using similar conditions with alanine or glycine as second amino acid, 2.6 g/L Arg-Ala or 2.4 g/L Arg Gly were produced. The RizA/AckA system selectively produced substantial amounts of arginyl dipeptides while minimizing the usage of the expensive ATP.

Highlights

  • IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations

  • Peptidases from basidiomycetes were used to produce protein hydrolysates enriched in salt-taste enhancing dipeptides [9]

  • The L-amino acid ligases (LALs) RizA from Bacillus subtilis NBRC3134 has a high specificity for producing dipeptides with an N-terminal arginine and is an ideal candidate for the synthesis of salt-taste enhancing dipeptides [11]

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Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Peptidases from basidiomycetes were used to produce protein hydrolysates enriched in salt-taste enhancing dipeptides [9]. The LAL RizA from Bacillus subtilis NBRC3134 has a high specificity for producing dipeptides with an N-terminal arginine and is an ideal candidate for the synthesis of salt-taste enhancing dipeptides [11]. The use of acetate kinase which regenerates ATP from ADP and acetyl phosphate (AcP). Through biocatalytic strategies such as the of phosphoric acid with acetic anhydride [13,18] or through biocatalytic strategies such as of phosphoric with acetic anhydride [13,18] Such as Resynthesis fromacid pyruvate and phosphate by pyruvate oxidase from Pediococcus [19].

Influence of Substrate
Influence of Cofactor Concentrations
Influence of Enzyme Concentrations
Influence of Temperature and pH
Materials and Methods
Cultivation and Expression
Purification
Biocatalysis
Analysis
Conclusions
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