Glutamine

Glutamine is a conditionally essential, non-essential amino acid that serves as the most abundant free amino acid in human plasma and intracellularly. It functions primarily as:

• A nitrogen carrier
• A substrate for rapid-dividing cells (e.g., enterocytes, immune cells, and fibroblasts)
• A key precursor for nucleotides, glutathione, and other amino acids, supporting both metabolic and immune processes.

• Glutamine (IUPAC: 2-amino-4-carbamoylbutanoic acid) has the molecular formula C₅H₁₀N₂O₃ and a molecular weight of 146.15 g mol⁻¹.
• It is a polar, non-ionic amino acid at physiological pH, possessing an α-amino group, a side-chain amide (–CONH₂), and a carboxylate group.
• The side-chain amide renders it a neutral amino acid, distinct from acidic (aspartate) or basic (lysine) residues.
• Its pKa values are ~2.2 (carboxyl) and ~9.1 (α-amino).
• The amide side chain is a key donor/acceptor for hydrogen bonding, influencing its solubility (≈1 g mL⁻¹ in water) and its role as a nitrogen donor in biosynthetic pathways.

• Dietary glutamine is abundant in protein-rich foods: beef, chicken, fish, dairy, eggs, and plant sources such as beans, lentils, and nuts.
• Commercial supplements are typically fermentation-derived from Corynebacterium glutamicum or Bacillus subtilis cultured on glucose-rich media, producing a high-purity L-glutamine powder.
• Some manufacturers use chemical synthesis (e.g., Strecker synthesis) for research-grade material, but most commercial products are biotechnologically produced, yielding >99 % purity with minimal residual solvents.
• Quality considerations include: verification of L-isomer (the biologically active form), absence of heavy metals or microbial contaminants, and certification (e.g., GMP, NSF).

All statements are based on peer-reviewed literature up to 2024; individual responses may vary, and consultation with a qualified health professional is recommended before initiating supplementation.