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Citrate and bead interference

The table below shows results from a compound interference study. We tested a panel of 24 compounds in a QC assay using our AlphaLISA® toolbox bead products. The information below can be used for guidance as to whether citrate might interfere in assays involving particular bead products, and at what citrate concentration interference might occur. These data are derived from single experiments and should serve more as a guide rather than a precise value, as it is unlikely you will be using the exact same assay design as used to generate the data below. Interference concentrations may vary depending on the assay components. It is possible your assay will tolerate higher or lower concentration than what is shown.

Tested up to 0.1M
Catalog NumberProductNo effect (10%)50% loss% of inhibition at max conc
AL125Streptavidin AlphaLISA Acceptor Beads1.7E-033.9E-03100
AL126Protein L AlphaLISA Acceptor Beads3.0E-033.6E-03100
AL127Anti-FITC AlphaLISA Acceptor Beads1.3E-032.1E-0399
AL128 (biotin)Anti-6xHis AlphaLISA Acceptor Beads7.5E-048.6E-04100
AL128 (GSH)Anti-6XHis AlphaLISA Acceptor Beads7.7E-049.4E-04100
AL129Anti-V5 AlphaLISA Acceptor Beads2.8E-068.9E-0598
AL130Anti-mouse IgM AlphaLISA Acceptor Beads9.5E-041.2E-03100
AL131Anti-chicken IgY AlphaLISA Acceptor Beads2.3E-032.8E-0399
AL132Anti-sheep IgG AlphaLISA Acceptor Beads2.5E-033.1E-03100
AL133Anti-GFP AlphaLISA Acceptor Beads2.1E-032.2E-03100
AL134Anti-MBP AlphaLISA Acceptor Beads2.4E-032.7E-03100
AL136Strep-Tactin AlphaLISA Acceptor Beads1.4E-032.6E-03100
AS102Protein A Alpha Donor Beads7.6E-054.9E-04100
AS103Anti-FLAG Alpha Donor Beads2.3E-032.5E-03100
AS104Anti-mouse IgG Alpha Donor Beads1.6E-032.5E-03100
AS105Anti-rabbit IgG Alpha Donor Beads1.7E-033.9E-03100
AS106Strep-Tactin Alpha Donor Beads9.4E-041.1E-03100
AL900AlphaLISA TruHits kit 2 ug/mL3.1E-02>0.149
AL900AlphaLISA TruHits kit 20 ug/mL1.8E-02>0.144

Refer to the figure below for more detail as to what the values in the table above indicate. Please note that the figure is provided as a general example to explain how the values in our interference tables were determined. The table above indicates that an assay testing the effect of citrate using anti-6X His AlphaLISA Acceptor beads (with glutathione Donor beads) showed little effect on the assay signal at final citrate concentrations up to 0.77 mM. Citrate did show a half-maximal inhibition of signal when used at a final concentration of 0.94 mM. When 0.1 M citrate was included in the assay, 100% signal inhibition was observed.

Figure: Key for how the values in our interference tables are derived. The “no effect” concentration was obtained by extrapolating the MAX - 10% MAX counts. Refer to the table above for actual interference values for each toolbox bead product.