Characterization of a glutamate decarboxylase (GAD) gene from Lactobacillus zymae |
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Authors: | Ji Yeong Park Seon-Ju Jeong Jeong Hwan Kim |
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Institution: | 1. Division of Applied Life Science (BK21 Plus), Graduate School, Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, Republic of Korea
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Abstract: | Lactic acid bacteria (LAB) were isolated from Kimchi, a Korean traditional fermented vegetable food. LAB accumulating GABA (γ-aminobutyric acid) in the culture media were screened by TLC analysis. One isolate, GU240, produced the highest amount of GABA among the 3,000 isolates and identified as a Lactobacillus zymae strain. Glutamate decarboxylase (GAD) gene was cloned and over-expressed in E. coli BL21(DE3) using pET26b(+). The recombinant GAD was purified by using a Ni–NTA column. Its size was 53 kDa by SDS-PAGE. Maximum GAD activity was at pH 4.5 and 41 °C and the activity was dependent on pyridoxal 5′-phosphate. Km and Vmax of LzGAD were 1.7 mM and 0.01 mM/min, respectively, when glutamate was used as a substrate. |
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