EKylation: Addition of an Alternating-Charge Peptide Stabilizes Proteins

Erik J. Liu, Andrew Sinclair, Andrew J. Keefe, Brent L. Nannenga, Brandon L. Coyle, François Baneyx, Shaoyi Jiang

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


For nearly 40 years, therapeutic proteins have been stabilized by chemical conjugation of polyethylene glycol (PEG), but recently zwitterionic materials have proved to be a more effective substitute. In this work, we demonstrate that genetic fusion of alternating-charge extensions consisting of anionic glutamic acid (E) and cationic lysine (K) is an effective strategy for protein stabilization. This bioinspired "EKylation" method not only confers the stabilizing benefits of poly(zwitterions) but also allows for rapid biosynthesis of target constructs. Poly(EK) peptides of different predetermined lengths were appended to the C-terminus of a native β-lactamase and its destabilized TEM-19 mutant. The EK-modified enzymes retained biological activity and exhibited increased stability to environmental stressors such as high temperature and high-salt solutions. This one-step strategy provides a broadly applicable alternative to synthetic polymer conjugation that is biocompatible and degradable.

Original languageEnglish (US)
Pages (from-to)3357-3361
Number of pages5
Issue number10
StatePublished - Oct 12 2015
Externally publishedYes

ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry


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