5365. Lanthionine

Nomenclature

CAS number: 922-55-4
S-[(2R)-2-Amino-2-carboxyethyl]-l-cysteine; 3,3′-thiodi-l-alanine; l-lanthionine; [R-(R*,R*)]-bis(2-amino-2-carboxyethyl)sulfide.
C6H12N2O4S; mol wt 208.24.
C 34.61%, H 5.81%, N 13.45%, O 30.73%, S 15.40%.

Description and references

A rare amino acid found in proteins; sulfide analog of cystine. First isolated as artifacts of wool hydrolysates. Isoln: M. J. Horn et al., J. Biol. Chem. 138, 141 (1941); from chick embryo: N. H. Sloane, K. G. Untch, Biochemistry 5, 2658 (1966); from silkworm and Japanese oak moth: D. R. Rao et al., ibid. 6, 1208. Synthesis: V. du Vigneaud, G. B. Brown, J. Biol. Chem. 138, 151 (1941). Structure studies: I. W. Stapleton, O. A. Weber, Int. J. Pept. Protein Res. 3, 243 (1971). Crystal structure: G. R. Desiraju, D. R. Rao, Acta Crystallogr. C46, 627 (1990).

Chemical structure

Properties

Elongated hexagonal plates. mp 295-296° (dec). [α]D25 +9.4° (c = 1.4 in 2.4N NaOH); [α]D22 +8.6° (c = 5 in 2.4N NaOH); [α]D22 +6.0° (c = 1 in 1N NaOH).

Derivative

meso-Form.

Properties

Six-sided plates having a triangular appearance from dil NH3. Softens at 270°, dec 304°. Stable to alkalies. Sol in dil acids and alkalies. Sparingly sol in water. Insol in alcohol, ether, chloroform, acetone.

Derivative

dl-Form.

Properties

Elongated hexagonal plates. Chars at 240°, dec 286-292°.

Derivative

d-Form.

Properties

Elongated hexagonal plates. Darkens at 245°, dec 293-295°. [α]D21 8.0° (c = 5 in 2.4N NaOH).