L-Cystine

Other Names: Cystine, [R-(R*,R*)]-3,3'-dithiobis(2-aminopropanoic acid)
Chemical Formula: C₆H₁₂N₂O₄S₂
Molar Mass: 240.30 g/mol
CAS Number: 56-89-3
Appearance: White crystalline material; powdered cystine appears white in the visible spectral range.

Chemical and Physical Properties

In the crystalline state, L-cystine molecules may adopt a zwitterionic form and crystallize in the hexagonal P6₁22 space group. The crystal structure contains hydrogen-bonded molecular layers, while the disulfide bond connecting the two cysteine-derived units is a central structural feature of the molecule.

The solubility of L-cystine in aqueous systems is strongly dependent on pH. Experimental measurements also showed that increasing sodium chloride concentration can increase L-cystine solubility under the investigated conditions, demonstrating the importance of ionic interactions in its solution behavior.

Applications

L-Cystine is used as a starting material in organic synthesis, including the preparation of cysteine-derived disulfide-reducing reagents.

It is widely employed as a model compound in research on crystallization, crystal growth and molecular recognition, particularly in studies investigating the formation and inhibition of L-cystine crystals.

L-Cystine has also been investigated as a functional biomolecular component of polymeric materials. Research has demonstrated its incorporation into polyurethane systems developed for controlled drug-delivery applications.

Safety