Cell surface labeling of Escherichia coli via copper(I)-catalyzed [3+2] cycloaddition

A. James Link, David A. Tirrell

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558 Scopus citations


Labeling of the cell surface of Escherichia coli was accomplished by expression of a recombinant outer membrane protein, OmpC, in the presence of the unnatural amino acid azidohomoalanine, which acts as a methionine surrogate. The surface-exposed azide moieties of whole cells were biotinylated via Cu(1)-catalyzed [3+2] azide-alkyne cycloaddition. The specificity of labeling of both wild-type OmpC and a mutant containing additional methionine sites for azidohomoalanine incorporation was confirmed by Western blotting. Flow cytometry was performed to examine the specificity of the labeling. Cells that express the mutant form of OmpC in the presence of azidohomoalanine, which were biotinylated and stained with fluorescent avidin, exhibit a mean fluorescence 10-fold higher than the background. Incorporation of an unnatural amino acid can thus be determined on a single-cell basis.

Original languageEnglish (US)
Pages (from-to)11164-11165
Number of pages2
JournalJournal of the American Chemical Society
Issue number37
StatePublished - Sep 17 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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