Cysteine and Glutathione in Catabolic States Semantic Scholar What is NAC (N Acetyl L Cysteine)?, NAC is a derivative of the amino acid L Cysteine, designed to be more stable and bioavailable than regular cysteine on its own., Lets break it down:, Cysteine l Cysteine Glutathione Mixed Disulfide, a Novel Bioavailable Sulfhydryl Modified Glutathione Precursor, Protects against Early Liver Injury Induced by Short Term Hypercholesterolemia Chemical Research in Toxicology Pentelute Lab MIT Enzymatic Click Ligation: Selective Cysteine Modification in Polypeptides Enabled by Promiscuous Glutathione S Transferase