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

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