Engineered C-N Lyase: Enantioselective Synthesis of Chiral Synthons for Artificial Dipeptide Sweeteners

Aspartic acid derivatives with branched N-alkyl or N-arylalkyl substituents are valuable precursors to artificial dipeptide sweeteners such as neotame and advantame. The development of a biocatalyst to synthesize these compounds in a single asymmetric step is an as yet unmet challenge. Reported here is an enantioselective biocatalytic synthesis of various difficult N-substituted aspartic acids, including N-(3,3-dimethylbutyl)-l-aspartic acid and N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-l-aspartic acid, precursors to neotame and advantame, respectively, using an engineered variant of ethylenediamine-N,N '-disuccinic acid (EDDS) lyase from Chelativorans sp. BNC1. This engineered C-N lyase (mutant D290M/Y320M) displayed a remarkable 1140-fold increase in activity for the selective hydroamination of fumarate compared to that of the wild-type enzyme. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step-economic synthesis of an important class of food additives.