Procysteine
Procysteine is an organic compound with the formula. It is a colorless solid. The compound is classified as a derivative of the heterocycle 2-oxo-1,3-thiazoline. Such rings are prepared by the action of phosgene (or related dehydration reagents on 2-aminoethanethiols, in this case cysteine:
The compound hydrolyzes to cysteine. The hydrolysis is catalyzed by 5-oxoprolinase.