Role of aminotransferases in glutamate metabolism of human erythrocytes

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Role of aminotransferases in glutamate metabolism of human erythrocytes


Abstract Human erythrocytes require a continual supply of glutamate to support glutathione synthesis, but are unable to transport this amino acid across their cell membrane. Consequently, erythrocytes rely on de novo glutamate biosynthesis from α-ketoglutarate and glutamine to maintain intracellular levels of glutamate. Erythrocytic glutamate biosynthesis is catalyzed by three enzymes, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and glutamine aminohydrolase (GA). Although the presence of these enzymes in RBCs has been well documented, the relative contributions of each pathway have not been established. Understanding the relative contributions of each biosynthetic pathway is critical for designing effective therapies for sickle cell disease, hemolytic anemia, pulmonary hypertension, and other glutathione-related disorders. In this study, we use multidimensional 1Hâ??13C nuclear magnetic resonance (NMR) spectroscopy and multiple reaction mode mass spectrometry (MRM-MS) to measure the kinetics of de novo glutamate biosynthesis via AST, ALT, and GA in intact cells and RBC lysates. We show that up to 89% of the erythrocyte glutamate pool can be derived from ALT and that ALT-derived glutamate is subsequently used for glutathione synthesis.

• Content Type Journal Article
• Pages 1-9
• DOI 10.1007/s10858-011-9481-9
• Authors
  • James J. Ellinger, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
  • Ian A. Lewis, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
  • John L. Markley, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA

• • Journal Journal of Biomolecular NMR
  • Online ISSN 1573-5001
  • Print ISSN 0925-2738

Source: Journal of Biomolecular NMR