L-aspartic acid derivatives as precursors of aspartyl-dipeptide sweeteners - I. Synthesis of L-aspartic acid by biocatalytical reductive amination of fumaric acid

L-aspartic acid and its N-substituted derivatives are used as carboxylic components of dipeptides in the research of molecular bases of sweet taste dipeptide ligands. This work refers to experiments performed in order to obtain L-aspartic acid by stereo selective transformation of fumaric acid in enzymatic catalysis. The biocatalyst used for this purpose was obtained by immobilization of E. Coli cells having high aspartase activity The most active immobilized cells were obtained by the entrapment in cross linked polyacrylamide gel method and additional treatment with glutardialdehyde, for which important parameters, like concentration of monomer, cross linking reagent and glutardialdehyde were studied. Kinetics of enzymatic reaction with immobilized biocatalyst was studied. Conditions for the enzymatic conversion of fumaric acid into L-aspartic acid using immobilized active cells were also investigated.