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Pivotal Enzyme in Glutamate Metabolism of Poly-g-Glutamate-Producing Microbes
Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan
* Author to whom correspondence should be addressed.
Received: 9 November 2012; in revised form: 28 January 2013 / Accepted: 5 February 2013 / Published: 6 February 2013
Abstract: The extremely halophilic archaeon Natrialba aegyptiaca secretes the L-homo type of poly-g-glutamate (PGA) as an extremolyte. We examined the enzymes involved in glutamate metabolism and verified the presence of L-glutamate dehydrogenases, L-aspartate aminotransferase, and L-glutamate synthase. However, neither glutamate racemase nor D-amino acid aminotransferase activity was detected, suggesting the absence of sources of D-glutamate. In contrast, D-glutamate-rich PGA producers mostly possess such intracellular sources of D-glutamate. The results of our present study indicate that the D-glutamate-anabolic enzyme “glutamate racemase” is pivotal in the biosynthesis of PGA.
Keywords: L-glutamate sources; glutamate racemase; PGA chirality; archaea; bacteria
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Ashiuchi, M.; Yamamoto, T.; Kamei, T. Pivotal Enzyme in Glutamate Metabolism of Poly-g-Glutamate-Producing Microbes. Life 2013, 3, 181-188.
Ashiuchi M, Yamamoto T, Kamei T. Pivotal Enzyme in Glutamate Metabolism of Poly-g-Glutamate-Producing Microbes. Life. 2013; 3(1):181-188.
Ashiuchi, Makoto; Yamamoto, Takashi; Kamei, Tohru. 2013. "Pivotal Enzyme in Glutamate Metabolism of Poly-g-Glutamate-Producing Microbes." Life 3, no. 1: 181-188.