N-(L-isoaspartyl)-L-cysteine -17.026548385620117188 -17.030000686645507812 201.03338623046875 201.2299957275390625 (S)-2-amino-4-((R)-1-carboxy-2-sulfanylethyl)amino-4-oxobutanoic acid natural N-(L-isoaspartyl)-L-cysteine 2-amino-N4-(1-carboxy-2-mercaptoethyl)butanediamic acid PSI-MOD CROSSLNK Isoaspartyl cysteine isopeptide (Cys-Asn) A protein modification that effectively crosslinks L-aspartic acid and L-cysteine residues via an isopeptide bond to form N-(L-isoaspartyl)-L-cysteine. N-term Cross-link 2. N-isoaspartyl cysteine C 7 H 9 N 2 O 3 S 1 H -3 N -1 2-(3-amino-3-carboxypropanoyl)amino-3-mercaptopropanoic acid MOD:00221 C, N N-beta-aspartylcysteine isopeptide crosslinked residues crosslinked residues with loss of ammonia crosslinked L-asparagine residue crosslinked L-cysteine residue