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  Reference Spotlight

The reliable assessment of monoclonal antibody (mAb) affinity against membrane proteins in vivo is a major issue in the development of cancer therapeutics. We describe here a simple and highly sensitive method for the evaluation of mAbs against membrane proteins by means of a kinetic exclusion assay (KinExA) in combination with our previously developed membrane protein display system using budded baculovirus (BV). In our BV display system, the membrane proteins are displayed on the viral surface in their native form. The BVs on which the liver cancer antigen Roundabout 1 (Robo1) was displayed were adsorbed onto magnetic beads without fixative (BV beads). The dissociation constant (Kd, ∼10(-11) M) that was measured on the Robo1 expressed BV beads correlated well with the value from a whole cell assay (the coefficient of determination, R(2) = 0.998) but not with the value for the soluble extracellular domains of Robo1 (R(2) = 0.834). These results suggest that the BV-KinExA method described here provides a suitably accurate Kd evaluation of mAbs against proteins on the cell surface.

Kusano-Arai 0., et al. 2016. Kinetic exclusion assay of monoclonal antibody affinity to the membrane protein Roundabout 1 displayed on baculovirus. Anal Biochem. 10.1016/j.ab.2016.04.004.

KinExA References

Affinity & Kinetic Measurements:

KinExA technology overview:

KinExA’s role in drug discovery:

Significance of “solution phase” measurements to unmodified molecules:

Comparison to SPR:

Sensitivity to measure tight binders:

Reverse assay techniques:

Whole cell binding techniques:

  • Bedinger, D., et al. 2015. Differential pathway coupling of activated insulin receptor drives signaling selectivity by XmetA, an allosteric partial agonist antibody. J Pharmacol Exp Ther 353(1):35-43.
  • Rathanaswami P., Babcook J., Gallo M. 2008. High-affinity binding measurements of antibodies to cell-surface-expressed antigens. Anal Biochem 373: 52-60.
  • Xie L., et al. 2005. Measurement of the functional affinity constant of a monoclonal antibody for cell surface receptors using kinetic exclusion fluorescence immunoassay. J Immunol Methods 304: 1-14.

Unpurified antigens:

Other interesting studies:

  • Li X., Kaattari S.L., Vogelbein M.A., Vadas G.G., Unger M.A., 2016. A highly sensitive monoclonal antibody based biosensor for quantifying 3-5 ring polycyclic aromatic hydrocarbons (PAHs) in aqueous environmental samples. Sens Biosensing Res. 7:115-120.
  • Lou J., et al. 2010. Affinity maturation of human botulinum neurotoxin antibodies by light chain shuffling via yeast mating. Protein Eng Des Sel 23(4): 311-319.
  • Kahle K.M., Steger H.K., Root M.J. 2009. Asymmetric deactivation of HIV-1 gp41 following fusion inhibitor binding. PLOS Path 5(11): 1-11.
  • Nowakowski A., et al. 2002. Potent neutralization of botulinum neurotoxin by recombinant oligoclonal antibody. Proc Natl Acad Sci 99: 11346-11350.

Immunoassay Techniques:

  • Darwish I.A., et al. 2013. Kinetic-exclusion analysis-based immunosensors versus enzyme-linked immunosorbent assays for measurement of cancer markers in biological specimens. Talanta 111: 13-19.
  • Prieto-Simon B., Miyachi H., Karube I., Saiki H. 2010. High-sensitive flow-based kinetic exclusion assay for okadaic acid assessment in shellfish samples. Biosens Bioelectron 25: 1395-1401.
  • Sasaki K., Oguma S., Namiki Y., Ohmura N. 2009. Monoclonal antibody to trivalent chromium chelate complex and its application to measurement of the total chromium concentration. Anal Chem 81: 4005-4009.
  • Glass T.R., Ohmura N., Saiki H. 2007. Least detectable concentration and dynamic range of three immunoassay systems using the same antibody. Anal Chem 79: 1954-1960.
  • Bromage E.S., et al. 2007. The development of a real-time biosensor for the detection of trace levels of trinitrotoluene (TNT) in aquatic environments. Biosens Bioelectron 22: 2532-2538.
  • Sasaki K., Glass T.R., Ohmura N. 2005. Validation of accuracy of enzyme-linked immunosorbent assay in hybridoma screening and proposal of an improved screening method. Anal Chem 77: 1933-1939.
  • Glass T.R., et al. 2004. Use of excess solid-phase capacity in immunoassays: advantages for semicontinuous, near-real-time measurements and for analysis of matrix effects. Anal Chem 76: 767-772.
  • Ohmura N., Lackie S., Saiki H. 2001. An immunoassay for small analytes with theoretical detection limits. Anal Chem 73: 3392-3399.