N-acetyl-L-cysteine (2R)-2-acetamido-3-sulfanylpropanoic acid 146.0275726318359375 146.17999267578125 2-acetylamino-3-mercaptopropanoic acid 2-acetylamino-3-sulfanylpropanoic acid 2-acetylazanyl-3-sulfanylpropanoic acid 42.01056671142578125 42.04000091552734375 A protein modification that effectively converts an L-cysteine residue to N-acetyl-L-cysteine. Acetyl C C 2 H 2 N 0 O 1 S 0 C 5 H 8 N 1 O 2 S 1 MOD:00052 MOD_RES N-acetylcysteine N-acetyl-L-cysteine N-acetylated cysteine N-acetylcysteine N-term NAcCys PSI-MOD incidental to RESID:AA0223 natural uniprot.ptm:PTM-0201 monoacetylated L-cysteine alpha-amino acetylated residue