Title: Cysteic Acid
CAS Registry Number: 13100-82-8
CAS Name: 3-Sulfoalanine
Additional Names: a-amino-b-sulfopropionic acid
Molecular Formula: C3H7NO5S
Molecular Weight: 169.16
Percent Composition: C 21.30%, H 4.17%, N 8.28%, O 47.29%, S 18.96%
Line Formula: HOOCCH(NH2)CH2SO3H
Literature 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).
Derivative Type: L-Form
Properties: Octahedra or needles from dil alc (also forms a monohydrate, prismatic needles). When anhydr, dec 260°. [a]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.
pKa: pKa1 (25°): 1.89; pKa2 8.7; pKb about 12.7
Optical Rotation: [a]D20 +8.66° (1.85 g in 25 ml)
Derivative Type: DL-Form
Properties: Crystals, dec 245°.
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