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January 1969

β-Mercaptolactate-Cysteine Disulfide in the Urine of a Mentally Retarded Patient

Author Affiliations

From the Medical Professorial Unit, St. Bartholomew's Hospital, London. Doctor Crawhall is now with the Department of Medicine, Royal Victoria Hospital, Montreal.

Am J Dis Child. 1969;117(1):71-82. doi:10.1001/archpedi.1969.02100030073008

A SULFUR-containing amino acid in the urine of a mentally deficient patient, observed by Ampola et al,1 did not correspond in its chromatographic properties to any previously described amino acid. The patient was born following a brother-sister mating and the mental and physical findings have been described in the previous paper.1 The method of isolation, purification, and characterization of this amino acid followed by partial synthesis will be described. The amino acid, which was shown to be β-mercaptolactate-cysteine disulfide (compound 1) was isolated from the urine by the methods of preparative column chromatography described in reference 1 and was then in the form of an oil and contained some ninhydrin positive and ninhydrin negative impurities as well as urinary pigments. Intermolecular disulfide exchange of compound 1 can occur, which gives rise to cystine and β-mercaptolactate disulfide. The latter was isolated (compound 2) and its structure was confirmed by