Unique antibody KD determination platform
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Antibody affinity measurement by SPR, SPRi or Octet.
Even compatible with high throughput KD determination.
We are one of the only service providers proposing antibody KD determination by SPRi.
No additional lead time, no extra cost, no artifact or bias (occluded binding site, false hydrophobic interaction)
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Get your antibody KD values in 2/3 weeks.
Having already developed and characterized 300+ monoclonal antibodies for various customers, ProteoGenix acquired strong expertise in biomolecular interaction analysis. Whether your project requires high throughput KD determination or crude sample analysis (cell, bacteria…), we have everything in hand to bring the most suitable solution to match your requirements.
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We were asked by a customer to measure the anti-protein X antibody binding affinity against a transmembrane protein X expressed at the surface of 293T cells. Expressing and presenting the protein directly in the cell allowed us to present the extracellular epitope while maintaining its native conformation.
Measurements were performed using Surface Plasmon Resonance Imaging technology (Horiba XelPlex).
The biochip was modified using a classical amine coupling strategy. Briefly, a –COOH terminated surface was activated using EDC/NHS leading to a reactive sulfo-NHS ester. This intermediate is known to react with primary amine to form a stable amide linkage. 2 anti-X antibody deposition methods were further tested in order to determine the optimal spotting approach (details provided in the PDF file).
X protein cells specific binding was tested by comparing the kinetic curves obtained by injecting X protein cells and control cells (293T cells transfected by an empty plasmide) over an anti-protein X antibody modified biochip.
Comparison of X protein cell and control cell injections on the anti-protein X antibody modified biochip led to clear differences in the kinetic curves whatever the conditions of immobilization.
Therefore, the data obtained demonstrates specific binding of X protein cells to anti-protein X antibody.
Kinetic curves were obtained by injecting X protein cells over the anti-X protein antibody modified surface at different concentrations. The deposition method that was chosen is the one that gave best results in the aforementioned study.
Kinetics parameters were determined by fitting the curves at different concentrations using a 1:1 interaction model. Antibody KD value was obtained by calculating the kd/ka ratio.
Specific binding of X protein cells to the anti-X protein antibody was demonstrated by SPRi. SPRi signals allowed the measurement of a low apparent KD which can be interpreted as high affinity antibody-cell interaction. This binding affinity is mainly governed by a high association rate (ka). The multiplexing configuration of SPRi allowed immobilizing the anti-X protein antibody on a same biochip with the two different immobilization methods and at four different concentrations for each immobilization method. During this experiment, 8 different experimental conditions were tested and 282 different sensorgrams were generated in a single biochip.
Click on the button below to get the complete report “Binding study between an anti-X protein antibody and the X protein expressed at the surface of 293T cells by Surface Plasmon Resonance imaging (SPRi) technology”
We were requested by a customer to measure the KD of an antibody/antigen interaction via Biacore. The project dealt with the affinity ranking of 5 different antibodies against a same antigen.
Antigen was immobilized on the dextran coated biochip surface via classical maleimide chemistry leading to stable covalent thioether bonding. Solutions containing the antibodies at various concentrations were then flown over the antigen. Measurement of the SPR signal at different antibody concentrations allowed the determination of the kinetics parameters (on-rate ka, off-rate kd) and thermodynamic parameters (KD).
The antibody/antigen binding affinity can be deduced from the kd/ka ratio leading to the possibility to deduce the affinity ranking.
Antibody affinity ranking can be deduced directly from the antibody KD value as the lower the KD value the higher the affinity of the antibody.
Antibody KD ranking: C<D<E<A<B
Antibody affinity ranking: C>D>E>A>B
Biacore analysis led to the conclusion that all 5 antibodies tested demonstrate high affinity against the antigen with C being the best for various reasons:
Click on the button below to get the complete report “Determination of KD of antibody/antigen interaction via Surface Plasmon Resonance (SPR) technology (Biacore X100)”