Effect of fluorescently labeling protein probes on kinetics of protein-ligand reactions

Y. S. Sun, J. P. Landry, Y. Y. Fei, X. D. Zhu, J. T. Luo, X. B. Wang, Kit Lam

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


Westudied the effect of fluorescently labeling proteins on protein-ligand reactions. Unlabeled ligands (streptaVidinbinding peptides and rabbit immunoglobulinG(IgG) as antigen targets) are immobilized on epoxy-functionalized glass slides. Unlabeled and Cy3-labeled protein probes from the same batch (streptavidin and goat antibodies) subsequently react with the surface-immobilized targets. By monitoring in situ the surface mass density change using an obliqueincidence reflectivity difference scanning microscope (a label-free detector), we measured k on and k off for streptavidin-peptide reactions and antibody-antigen reaction. We found that (1) equilibrium dissociation constants, defined as KD ) k off/k on, for streptavidin-peptide reactions increases by a factor of 3-4 when the solution-phase streptavidin is labeled with Cy3 dye and (2) K D for reactions of solution-phase goat anti-rabbit antibodies with rabbit IgG targets also change significantly when the goat antibodies are labeled with Cy3 dye.

Original languageEnglish (US)
Pages (from-to)13399-13405
Number of pages7
Issue number23
StatePublished - Dec 2 2008

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy


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