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Glutaminase catalyzes reaction of glutamate to GABA.

ABSTRACT: Here, for the first time, we report an NMR spectroscopy study of l-Glutamine (Gln) conversion by Glutaminase (Glnase), which shows that the reaction involves two distinct steps. In the first step, Glnase rapidly hydrolyzes Gln to Glutamate (Glu) (?16.87 ?mol of Gln/min/mg of Glnase) and in the second step, Glu generated in the first step is decarboxylated into gamma-amino butyric acid (GABA) with a much slower rate (?0.185 ?mol/min/mg). When Glnase was added to the sample containing l-Glu alone, it was also converted to GABA, at a similar rate as in the second step mentioned above. The rate of Glu decarboxylation into GABA by Glnase is about an order of magnitude lower than that by commonly known enzyme, Glutamate decarboxylase. Potential impact of these findings, on the mechanistic aspects of Gln-Glu shuttle in neuroscience and glutaminolysis in tumors, is discussed.

SUBMITTER: Nanga RP

PROVIDER: S-EPMC4097173 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature

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Glutaminase catalyzes reaction of glutamate to GABA.

Nanga Ravi Prakash Reddy RP DeBrosse Catherine C Singh Anup A D'Aquilla Kevin K Hariharan Hari H Reddy Ravinder R

Biochemical and biophysical research communications 20140419 4

Here, for the first time, we report an NMR spectroscopy study of l-Glutamine (Gln) conversion by Glutaminase (Glnase), which shows that the reaction involves two distinct steps. In the first step, Glnase rapidly hydrolyzes Gln to Glutamate (Glu) (∼16.87 μmol of Gln/min/mg of Glnase) and in the second step, Glu generated in the first step is decarboxylated into gamma-amino butyric acid (GABA) with a much slower rate (∼0.185 μmol/min/mg). When Glnase was added to the sample containing l-Glu alone, ...[more]

PMID: 24755074

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