Skip to main content


Table 2 Major metabolites and functions of NEAA in nutrition and metabolism

From: Biochemical and physiological bases for utilization of dietary amino acids by young Pigs

NEAA Metabolites or direct action Major functions
NEAA Proteins Structural components of the body; cell growth, development, and function
  Peptides Hormones, antibiotics, and antioxidants
Alanine Directly Inhibition of pyruvate kinase and hepatic autophagy; gluconeogenesis;
   transamination; glucose-alanine cycle; interorgan metabolism and transport of
   both carbon and nitrogen
Arginine Directly Activation of MTOR signaling; antioxidant; regulation of hormone secretion;
   allosteric activation of N-acetylglutamate synthase; ammonia detoxification;
   regulation of gene expression; immune function; activation of tetrahydro-
   biopterin synthesis; N reservoir; methylation of proteins
  Nitric oxide Signaling molecule; regulator of nutrient metabolism, vascular tone,
   hemodynamics, angiogenesis, spermatogenesis, embryogenesis, fertility,
   immune function, hormone secretion, wound healing, neurotransmission,
   tumor growth, mitochondrial biogenesis and function
  Ornithine Ammonia detoxification; syntheses of proline, glutamate and polyamines;
   mitochondrial integrity; wound healing
Asparagine Directly Cell metabolism and physiology; regulation of gene expression and immune
   function; ammonia detoxification; function of the nervous system
Aspartate Directly Purine, pyrimidine, asparagine, and arginine synthesis; transamination;
   urea cycle; activation of NMDA receptors; synthesis of inositol and β-alanine
  D-Aspartate Activation of NMDA receptors in brain
Cysteine Directly Disulfide linkage in protein; transport of sulfur
  Taurine Antioxidant; regulation of cellular redox state; osmolyte
  H2S A signaling molecule to regulate bloo flow, immunity, and neurological function
Glutamate Directly Glutamine, citrulline, and arginine synthesis; bridging the urea cycle with the
   Krebs cycle; transamination; ammonia assimilation; flavor enhancer; activation of NMDA receptors; N-acetylglutamate synthesis
  GABA Inhibitory or excitatory neurotransmitter depending on region in brain and type
   of receptor; regulation of neuronal excitability of throughout the nervous
   system; modulation of muscle tone; inhibition of T-cell response and inflammation
Glutamine Directly Regulation of protein turnover through cellular MTOR signaling, gene
   expression, and immune function; a major fuel for rapidly proliferating cells;
   inhibition of apoptosis; syntheses of purine, pyrimidine, ornithine, citrulline, arginine, proline, and asparagines; N reservoir ; synthesis of NAD(P)
  Glu and Asp Excitatory neurotransmitters; components of the malate shuttle; cell
   Metabolism; ammonia detoxification; major fuels for enterocytes
  GlcN6P Synthesis of aminosugars and glycoproteins; inhibition of nitric oxide synthesis; anti-inflammation; angiogenesis
  Ammonia Renal regulation of acid–base balance; synthesis of glutamate and carbamoyl- phosphate
Glycine Directly Calcium influx through a glycine-gated channel in the cell membrane; purine and serine synthesis; synthesis of porphyrins; inhibitory neurotransmitter in the central nervous system; co-agonist with glutamate for
   NMDA receptors; antioxidant; anti-inflammation; one-carbon-unit metabolism
  Heme Hemoproteins (e.g., hemoglobin, myoglobin, catalase, and cytochrome c);production of carbon monoxide (a signaling molecule)
Proline Directly Collagen structure and function; neurological function; osmoprotectant;
   activation of MTOR; a sensor of cellular energy status; an antioxidant;
   a regulator of the differentiation of cells (including embryonic stem cells)
  H2O2 Killing pathogens; intestinal integrity; a signaling molecule; immunity
  P5C Cellular redox state; DNA synthesis; lymphocyte proliferation; ornithine,
   citrulline, arginine and polyamine synthesis; gene expression; stress response
  OH-proline Structure and function of collagen
Serine Directly One-carbon-unit metabolism; syntheses of cysteine, purine, pyrimidine,
   ceramide and phosphatidylserine; synthesis of tryptophan in bacteria;
   gluconeogenesis (particularly in ruminants); protein phosphorylation
  Glycine Many metabolic and regulatory functions
  Choline A component of acetylcholine (a neurotransmitter), phosphatidylcholine (a
   structural lipid in the membrane), betaine (a methyl donor in the one-carbon- unit metabolic pathways)
  D-Serine Activation of NMDA receptors in brain
Tyrosine Directly Protein phosphorylation, nitrosation, and sulfation
  Dopamine Neurotransmitter; regulation of immune response
  EPN & NEPN Neurotransmitters; cell metabolism
  Melanin Antioxidant; inhibition of the production of inflammatory cytokines and
   superoxide; immunity; energy homeostasis; sexual activity; stress response
  T3 and T4 Regulation of energy and protein metabolism, as well as growth
Cys, Glu & Gly Glutathione Free radical scavenger; antioxidant; cell metabolism (e.g., formation ofleukotrienes, mercapturate, glutathionylspermidine, glutathione-nitric oxideadduct and glutathionylproteins); signal transduction; gene expression; apoptosis; cellular redox; immune response
Gln, Asp & Gly Nucleic acids Coding for genetic information; gene expression; cell cycle and function; protein and uric acid synthesis; lymphocyte proliferation
  1. EPN, epinephrine; GABA, γ-Aminobutyrate; GlcN6P, glucosamine-6-P; HMB, β-hydroxy-β-methylbutyrate; MTOR, mechanistic target of rapamycin; NEPN, norepinephrine; NOS, nitric oxide synthase; T 3 , triiodothyronine; T 4 , thyroxine.