Versatile fluorescence probes of protein kinase activity

J Am Chem Soc. 2003 Nov 26;125(47):14248-9. doi: 10.1021/ja0380502.


We introduce a versatile fluorescent peptide reporter of protein kinase activity. The probe can be modified to target a desired kinase by changing the kinase recognition motif in the peptide sequence. The reporter motif contains the Sox amino acid, which generates a fluorescence signal when bound to Mg2+ present in the reaction mixture. The phosphorylated peptide exhibits a much greater affinity for Mg2+ than its unphosphorylated analogue and, thus, a greater fluorescence intensity. Product formation during phosphorylation by the kinase is easily followed by the increase in fluorescence intensity over time. These probes exhibit a 3-5-fold increase in fluorescence intensity upon phosphorylation, the magnitude of which depends on the substrate. Peptides containing the reporter functionality are phosphorylated on serine by Protein Kinase C and cAMP-dependent protein kinase and are shown to be good substrates for these enzymes. The principle of this design extends to peptides phosphorylated on threonine and tyrosine.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Fluorescent Dyes / chemical synthesis
  • Fluorescent Dyes / chemistry*
  • Kinetics
  • Peptides / chemistry
  • Peptides / metabolism
  • Phosphorylation
  • Protein Kinases / chemistry
  • Protein Kinases / metabolism*
  • Spectrometry, Fluorescence


  • Fluorescent Dyes
  • Peptides
  • Protein Kinases