Capture-Tag-Release: A Strategy for Small Molecule Labeling of Native Enzymes

Chembiochem. 2016 Sep 2;17(17):1602-5. doi: 10.1002/cbic.201600267. Epub 2016 Jul 20.


A strategy for labeling native enzymes in a manner that preserves their activity is reported: capture-tag-release (CTR). Key to this approach is the small molecule CTR probe that contains an enzyme inhibitor, benzophenone crosslinker, and aryl phosphine ester. After UV-derived capture of the enzyme, addition of an azide-containing tag triggers a Staudinger ligation that labels the enzyme. A further consequence of the Staudinger ligation is fragmentation of the CTR probe, thus releasing the inhibitor and restoring enzymatic activity. As a proof-of-principle, the CTR strategy was applied to the hydrolase β-galactosidase. The enzyme was efficiently labeled with biotin, and the kinetic data for the biotinylated enzyme were comparable to those for unlabeled β-galactosidase. The CTR probe exhibits excellent targeting specificity, as it selectively labeled β-galactosidase in a complex protein mixture.

Keywords: Staudinger ligation; click chemistry; hydrolases; photoaffinity labeling; protein modifications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biotin / analysis
  • Biotin / chemistry
  • Kinetics
  • Molecular Structure
  • Small Molecule Libraries / analysis*
  • Small Molecule Libraries / chemical synthesis
  • Small Molecule Libraries / chemistry*
  • Staining and Labeling / methods*
  • Substrate Specificity
  • beta-Galactosidase / analysis*
  • beta-Galactosidase / chemistry
  • beta-Galactosidase / metabolism*


  • Small Molecule Libraries
  • Biotin
  • beta-Galactosidase