2780. Cysteic Acid

Nomenclature

CAS number: 13100-82-8
3-Sulfoalanine; α-amino-β-sulfopropionic acid; dl-cysteic acid.
C3H7NO5S; mol wt 169.16.
C 21.30%, H 4.17%, N 8.28%, O 47.29%, S 18.96%.

Description and references

Has been isolated from human hair oxidized with permanganate: Lissizin, Z. Physiol. Chem. 173, 309 (1928). Occurs normally in the outer part of the sheep's fleece, where the wool is exposed to light and weather: Martin, Synge, Adv. Protein Chem. 2, 3 (1945). Prepd from cystine or cysteine by oxidation with bromine in water: Friedmann, Beitr. Chem. Physiol. Pathol. 3, 25, 38; Gortner, Hoffman, J. Biol. Chem. 72, 435 (1927).

Chemical structure

Properties

Crystals, dec 245°.

Derivative

l-Form.

Nomenclature

CAS number: 498-40-8

Properties

Octahedra or needles from dil alc (also forms a monohydrate, prismatic needles). When anhydr, dec 260°. [α]D20 +8.66° (1.85 g in 25 ml). pKa1 (25°): 1.89; pKa2 8.7; pKb about 12.7. Soluble in water. Insol in alcohol.