Cysteine thiosulfonate in cystine metabolism

A sulfur-containing amino acid was observed in mammalian cystine metabolism, in vitro and in vivo , which we have characterized as 2-amino, 3-(thio-thiosulfonate)propionic acid (cysteine thiosulfonate). Its biosynthetic pathway appears to initiate with the cleavage of cystine by cystathionine γ-lyase to form thiocystine, which undergoes sulfinolysis to form cysteine thiosulfonate.