NOVEL GLUTAMATE DECARBOXYLASE VARIANT FOR SALT-FREE REACTION

摘要

The present invention relates to the development of a novel glutamate decarboxylase (GAD) exhibiting activity even at neutral pH, and to a method for producing gamma-aminobutyric acid (GABA) from high-concentration L-glutamate by using a catalyst in the form of the enzyme itself or cells containing the enzyme. More specifically, the novel glutamate decarboxylase variant is produced by adding a histidine tag for cleavage to the amino terminal of wild-type glutamate decarboxylase and eliminating carboxyl-terminal threonine or adding an excess of residual-group alanine, thereby expanding the active pH range towards neutral compared with the wild type, improving also the gamma-aminobutyric acid synthesis efficiency compared with the wild type and exhibiting almost 100% conversion efficiency, and thus a reaction system is developed in which the active pH range is expanded and glutamate is used as a buffering agent as well as constituting the substrate, and salt-free gamma-aminobutyric acid which is harmless to the body can be produced and absorbed.