title: Purification, properties and cDNA cloning of glutamate decarboxylase in germinated faba bean (Vicia faba L.).
abstract: Gamma-aminobutyric acid (GABA) is a non-protein amino acid with bioactive functions in humans. In this work, glutamate decarboxylase (EC 4.1.1.15, GAD) which is key in the GABA bioformation was purified from 5-day germinated faba beans and characterized. A single band was observed at 58 kDa using sodium dodecyl sulphate gel electrophoresis. GAD optimal activity was at pH 6.0 at 40°C with a K(m) value for glutamic acid (Glu) of 2.63 mM. The enzyme was inhibited significantly by Cu(2+), Fe(3+), Mg(2+), Ba(2+), aminoxyacetate, EGTA, Na(2)EDTA, l-cysteine and beta-mercaptoethanol; and activated at low Ca(2+) 0.2mM. Using RT-PCR, the GAD cDNA was sequenced which indicated 1787 bp long, containing a 1527 bp open reading frame (ORF) that encoded 509 amino-acid peptides with a calculated molecular weight of 57.74 kDa and a pI of 5.41 (GenBank accession number: JX444699).
authors: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors: Runqiang
authors: R
authors: Yang
authors: Yongqi
authors: Y
authors: Yin
authors: Qianghui
authors: Q
authors: Guo
authors: Zhenxin
authors: Z
authors: Gu
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004795:Enzyme Stability; D018525:Germination; D005968:Glutamate Decarboxylase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D012639:Seeds / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D013379:Substrate Specificity; D031307:Vicia faba / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D005968:Glutamate Decarboxylase