Cystine-copper complex

Cysteine and cystine has been determined in seawater by a method based on cathode stripping voltammetry of the copper complex [327]. 

Mechanism of Action A heavy metal antagonist that chelates copper, iron, mercury, lead to form complexes, promoting excretion of copper. Combines with cystine-forming complex, thus reducing concentration of cystine to below levels for formation of cystine stones. Exact mechanism for rheumatoid arthritis is unknown. May decrease cell-mediated immune response. May inhibit collagen formation. Therapeutic Effect Promotes excretion of copper, prevents renal calculi, dissolves existing stones, acts as anti-inflammatory drug. 

The positive CD Cotton effect at 260 nm and the negative Cotton effect at 274 nm may be at least partly attributed to amino-acid residues. The side-chain residues of L-cystine, L-phenylalanine. L-tyrosine or L-tryptophan cause Cotton effects at 250—310 nm (101). However, copper complexes of simple amino acids show CD extremes at 245— 290 nm. Therefore, some contribution to the 260 nm band of erythro-... 

Penicillamine forms stable, soluble complexes with copper, iron, mercury, lead, and other heavy metals that are excreted in urine it is particularly useful in chelating copper in patients with Wilson s disease. Penicillamine also combines with cystine alone, reducing free cystine below the level of urinary stone formation. 

Computer analysis of 160 potentiometrically determined equilibria ofCu , Zn ", and 17 amino acids (all simultaneously present) showed that 85% of the copper was present as a single complex (1 1 1 histidine/copper/cystine), and 67% of the zinc was bound by cysteine and histidine (Hallman, Perrin and Watt, 1971). 

Computer analysis of 160 potentiometrically determined equilibria of Cu, Zn , and 17 aminoacids (all simultaneously present) showed that 85 per cent of the copper was present as a single complex (1 1 i histidine-copper-cystine), and 67 per cent of the zinc was bound by cysteine and histidine (Hallman, Perrin, and Watt, 1971). This may reflect the situation in the blood-stream. The ternary complex histidine-copper-threonine (1 1 i) has been isolated from serum by thin layer chromatography, a method conducive to re-equilibration and hence not necessarily indicative of the picture in the blood-stream (Sarkar and Kruck, 1966). 

---