Figure 3.

No significant effect of the TD2 buffer was seen in either the rate of color development from the HRP conjugate or antigen affinity in commercial ELISA kits for (a) total human transferrin (Tf), (b and c) total human matrix metalloprotease 2 (MMP2) or 3 (MMP3), (d) total human V-akt murine thymoma viral oncogene homolog 1 (AKT1), or (e) soluble vascular endothelial growth factor receptor (sVEGFR). Apparent affinity constants (±one standard deviation) for separate serial dilutions for the kit standards are shown for each ELISA for both the recommended kit diluent and TD2 buffers. (Standard deviations are determined by partitioning the error of the estimate across the fitted parameters using the Jacobian matrix. In ELISA assays lacking experimental data defining the upper asymptotic limits of quantitation (e.g., VEGF R2 assay of Figure 3), this method produces very large errors when fitting the data with a nonlinear equation (1)).