
TY  - JOUR
A1  - Stapleton, IW 
A1  - Swan, JM 
T1  - Amino acids and peptides. VIII. The synthesis and some properties of L-cystine diamide
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1962
VL  - 15
IS  - 1
SP  - 106
EP  - 113
KW  - 
UR  - https://doi.org/10.1071/CH9620106 
N2  - L-Cystine diamide has been synthesized by several different routes and isolated as its crystalline di(trifluor0acetate) and dihydrochloride. The compound has a molecular rotation [M]D21 -630° in 1N HCl, compared to [M]D20 -537° for L-cystine ; the rotation is strongly dependent on pH in the range 5-8, the value of [M]D20 at pH 8 being -120°. The polarographic behaviour of L-cystine diamide is very similar to that of cystine. The amino groups in cystine diamide are only weakly basic, the pK?A values being 5.93 and 6.90 for the successive ionizations of the two NH3+ groups. The latter result is in accordance with the known acigenic properties of both amide and disulphide groups. A possible relation between optical rotation of cystine compounds and the pK? values of ionizable groups present in the molecule is discussed. 
ER  -

