Buffer-free production of gamma-aminobutyric acid using an engineered glutamate decarboxylase from Escherichia coli

Taek Jin Kang, Ngoc Anh Thu Ho, Seung Pil Pack

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Escherichia coli glutamate decarboxylase (GAD) converts glutamate into γ-aminobutyric acid (GABA) through decarboxylation using proton as a co-substrate. Since GAD is active only at acidic conditions even though pH increases as the reaction proceeds, the conventional practice of using this enzyme involved the use of relatively high concentration of buffers, which might complicate the downstream purification steps. Here we show by simulation and experiments that the free acid substrate, glutamic acid, rather than its monosodium salt can act as a substrate and buffer at the same time. This yielded the buffer- and salt-free synthesis of GABA conveniently in a batch mode. Furthermore, we engineered GAD to hyper active ones by extending or reducing the length of the enzyme by just one residue at its C-terminus. Through the buffer-free reaction with engineered GAD, we could synthesize 1. M GABA in 3. h, which can be translated into a space-time yield of 34.3. g/L/h.

Original languageEnglish
Pages (from-to)200-205
Number of pages6
JournalEnzyme and Microbial Technology
Volume53
Issue number3
DOIs
StatePublished - 15 Aug 2013

Keywords

  • Buffer-free enzyme reaction
  • Enzyme engineering
  • Gamma-aminobutyric acid
  • Glutamate decarboxylase

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