earticle

영어

Glutamate decarboxylase(GadB) from Escherichia coli is pyridoxal 5’phosphate-dependent enzyme which is catalyzing CO2 release from the alpha carboxyl group of L-glutamic acid to produce gamma amino butyric acid(GABA). GABA can be used as a monomer to synthesize a biobase and biodegradable polymer(polyamide 4). Gad is a key component of the most important acid resistance system, especially related to glutamic acid. GadB shows an acidic pH optimum(pH4~5) and becomes activated intracellularly because in extremely acidic environments protons leak through the bacterial cell membrane. In this research, gadB was highly expressed as soluble protein in Escherichia coli BL21(DE3) containing pET24a-gadB, which was induced by 0.5mM IPTG in LB medium. The Kcat/KM value was 24.8mM-1s-1. The highest product concentration was 102mM at pH 4.4 when we used 300mM glutamic acid as a substrate.