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Updated: Jan 26, 2026

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase
Published on: December 19, 2010
Identification of Lysine Misincorporation at Asparagine Position in Recombinant Insulin Analogs Produced in E. coli
Dorota Stadnik1, Anna Bierczyńska-Krzysik2, Joanna Zielińska2
1Łukasiewicz Research Network - Institute of Biotechnology and Antibiotics, Starościńska 5, 02-516, Warsaw, Poland. stadnikd@iba.waw.pl.
Purpose:
Identification of human insulin analogs' impurity with a mass shift +14 Da in comparison to a parent protein.
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.
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.
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