ChEBI: L-buthionine-(S,R)-sulfoximine is a 2-amino-4-(S-butylsulfonimidoyl)butanoic acid which has S-configuration. It is a inhibitor of gamma-glutamylcysteine synthetase and glutathione (GSH) biosynthesis and is capable of enhancing the apoptotic effects of several chemotherapeutic agents. It has a role as a ferroptosis inducer and an EC 6.3.2.2 (glutamate--cysteine ligase) inhibitor.