Valine is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, and a side chain isopropyl group, making it a non-polar aliphatic amino acid. L-Valine, the proteogenic enantiomer, is one of the three branched-chain amino acids and is essential in humans, requiring dietary intake. Chemical formula C5H11NO2 and molecular mass 117.15 g mol−1, valine has carboxyl and amino pKa values of approximately 2.39 and 9.74 respectively and an isoelectric point near 5.96. It is a white crystalline powder that is moderately soluble in water, stereochemically chiral at the α-carbon, and is produced industrially by microbial fermentation or chemical synthesis for use in nutrition, feed, cell culture media, and biochemical research. Analytical characterization typically uses chiral HPLC for enantiomeric purity, amino acid analysis for content, and mass spectrometry for related substances.
Parent: Valine
Typical specifications for food grade and pharmaceutical grade L-valine generally target high assay and low levels of related substances; a representative analytical specification is assay on dry basis ≥98.5%, water content (loss on drying) ≤0.5% and total ash ≤0.1%. Related amino acid impurities most commonly encountered are leucine and isoleucine as structural isomers, with individual limits commonly ≤0.5% and combined related substances limits typically ≤1.0%. D-valine (the enantiomer) is controlled and often specified ≤0.5% or by enantiomeric excess criteria. Typical degradation or related small-molecule impurities include 2-oxoisovaleric acid (alpha-ketoisovalerate) and small amounts of amino acid esters or peptides, often limited to ≤0.2% for a single degradant. Inorganic and elemental limits are commonly set as chloride and sulfate ≤0.05% each, and heavy metals ≤10 ppm; residual solvents are usually not detected or are controlled per relevant pharmacopeial limits. Exact impurity limits vary by grade and manufacturer and should be confirmed against the supplied certificate of analysis.
Valine functions as an essential amino acid in protein synthesis and branched-chain amino acid metabolism; it is used in dietary supplements, clinical and sports nutrition, animal feed formulations, cell culture media, and as a reagent in biochemical and pharmaceutical manufacturing.
High-valine foods are high-protein sources such as meat, poultry, fish, eggs, dairy products, soybeans and other legumes, peanuts and tree nuts, and whole grains; soy protein and animal proteins typically provide among the highest valine content per serving.
Yes, valine is classified as a neutral amino acid because its side chain is nonpolar and electrically neutral at physiological pH; the amino and carboxyl groups ionize according to their pKa values but the side chain does not carry a charge.
Valine contributes indirectly to skin health by supporting protein synthesis, tissue repair, and overall nutrition when supplied in adequate dietary amounts; topical cosmetic use of free amino acids can support moisture retention and formulation functionality, but specific benefits of topical valine are limited and should be evaluated on a product by product basis and in consultation with skincare or medical professionals.
