Cysteine-cystine identification

Sano, K., Yokozeki, K., Tamura, F., Yasuda, N., Noda, I. and Mitsugi, K. (1977) Microbial conversion of DL-2-amino A -thiazoline-4-carboxylic acid to L-cysteine and L-cystine screening of microorganisms and identification of products. Appl Environ Microbiol, 34, 806-810. 

Shanker, G., and Aschner, M. (2001). Identification and characterization of uptake systems for cystine and cysteine in cultured astrocytes and neurons Evidence for methylmercury-targeted disruption of astrocyte transport. J. Neurosci. Res. 66, 998-1002. 

The diagnosis of homocystinuria is based on the recognition of the clinical phenotype in conjunction with the identification of an elevated total plasma homocysteine and elevated plasma methionine concentrations (via quantitative plasma amino acid analysis). Low cystine and low cystathionine are also seen (Box 14.3). In addition, increased urinary excretion of homocysteine as well as cysteine-homocysteine disulfide can be identified on urine amino acid analysis. Confirmation of the diagnosis can be done via enzyme assay, typically performed on cultured skin fibroblasts, lymphocytes, or liver tissue, or via molecular studies. 

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