N-Acetylcystathionine: a New Urinary Amino-acid in Congenital Cystathioninuria

Abstract

WE recently described two children with congenital Cystathioninuria who enjoy excellent health, and show no evidence of neurological or mental disease associated with their metabolic disorder¹. Chromatography of their urines revealed not only cystathionine but also an unidentified ninhydrin-positive compound which, together with cystathionine, disappeared from urine when the children were given large doses of pyridoxine. The unknown compound appeared to be a thioether, based on its positive reaction to the chlorplatinate reagent, its negative reaction to cyanide followed by nitroprusside, and its replacement by a different ninhydrin-positive spot on paper chromatograms after urines had first been treated with hydrogen peroxide. We have isolated the unusual compound in relatively pure form from the urine of each of our patients, and have identified it as N-acetylcystathionine. This amino-acid has apparently not previously been encountered in nature.