L-Alanyl-L-Cystine, with the CAS number 115888-13-6, is a naturally occurring dipeptide composed of L-alanine and L-cystine linked by a peptide bond, also known as L-Ala-L-Cystine. Its molecular formula is C₈H₁₆N₂O₄S₂, and its molecular weight is 268.35 g/mol. As a bioactive dipeptide, it combines the physiological properties of its constituent amino acids, featuring good biocompatibility and unique chemical reactivity, making it widely used in biochemistry, pharmaceuticals, food, and cosmetic fields.
Physically, L-Alanyl-L-Cystine appears as a white to off-white crystalline powder or needle-like crystals. It has a melting point of approximately 220-225℃ (decomposition) and is soluble in water and hot ethanol, slightly soluble in cold ethanol, and insoluble in non-polar solvents. It is optically active, with a specific rotation [α]²⁰/D of -25.0° to -29.0° (in water, c=2), and remains stable under normal temperature and pressure when stored properly, with low hygroscopicity compared to other amino acid derivatives.
Chemically, it contains peptide bonds, amino groups, carboxyl groups, and disulfide bonds, which are the key functional groups determining its properties. The disulfide bond from L-cystine enables it to participate in redox reactions, while the peptide bond allows for controlled hydrolysis under specific conditions to release L-alanine and L-cystine. It is stable under neutral and weakly acidic conditions but may hydrolyze under strong acid, strong alkali, or high-temperature environments, maintaining its structural integrity in most common application systems.
Its core applications focus on biochemical research, pharmaceuticals, and daily chemicals. In biochemistry, it is used as a biochemical reagent for studying peptide metabolism, enzyme activity, and protein synthesis, and is widely applied in cell culture experiments. In the pharmaceutical industry, it serves as an intermediate for synthesizing peptide drugs, nutritional supplements, and antioxidants, supporting the development of products for maintaining skin health and regulating physiological functions. In cosmetics, it is added to skin care products to nourish the skin, enhance skin barrier function, and resist oxidative damage. Additionally, it is used as a food additive to improve nutritional value.
Safety-wise, it is generally recognized as safe (GRAS) for its intended uses, non-toxic and non-irritating under normal handling conditions. It should be stored in a sealed, cool, dry, and dark environment at 2-8℃, away from strong oxidants, moisture, and high temperatures, to prevent hydrolysis and degradation. With its excellent biocompatibility and versatile applications, it is an important raw material in biochemistry, pharmaceuticals, and daily chemical industries.
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