Conclusions
Although there are three asparagine residues in the insulin derivative, the misincorporation of lysine occurred only at position A21. The process involves G/U or A/U wobble base pairing.
Methods
The protein sequence variant was detected and identified with the application of peptide mapping, liquid chromatography, tandem mass spectrometric analysis, nuclear magnetic resonance spectroscopy (NMR) and Edman sequencing.
Purpose
Identification of human insulin analogs' impurity with a mass shift +14 Da in comparison to a parent protein.
Results
The misincorporated lysine (Lys) at asparagine (Asn) position A21 was detected in recombinant human insulin and its analogs. Conclusions: Although there are three asparagine residues in the insulin derivative, the misincorporation of lysine occurred only at position A21. The process involves G/U or A/U wobble base pairing.