Partial purification, characterization and cDNA cloning of aminoaldehyde dehydrogenase in germinated soybean (Glycine max L.)

γ-Aminobutyric acid (GABA) is a non-proteinous amino acid with some functions for human health. In this study, aminoaldehyde dehydrogenase (EC 1.2.1.19, AMADH) which has been proven to be an essential enzyme responsible for the GABA bioformation via polyamine degradation pathway was purified from 2-day germinated soybeans and characterized. The partially purified enzyme showed a single major band with a relative molecular mass of approximately 53.72 kDa-subunit using sodium dodecyl sulfate gel electrophoresis. AMADH exhibited the optimal activity at pH 8.0 and at 45 °C, respectively. The activity of purified AMADH was significantly inhibited by some heavy metal ions and sulfhydryl reagents. The cDNA of AMADH was sequenced by RT-PCR, which indicated 1,677 bp long and contained a 1,515 bp open reading frame that encoded 504 amino-acid peptides (GenBank accession number: KC478661).