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. 2013 Feb 7;8(2):e55617. doi: 10.1371/journal.pone.0055617

Figure 3. Dose-dependent binding by the recombinantly overexpressed and purified wild-type Mtd and L-Mtd to lysozyme and control proteins.

Figure 3

(A) ELISA experiments demonstrate that wild-type Mtd at the indicated concentrations on the X-axis fails to bind to the targeted proteins (coated at 200 nM concentrations) (n = 4). (B) L-Mtd at the indicated concentrations on the X-axis, however, binds with high affinity and specificity to lysozyme and not to the other targeted proteins (coated at 200 nM concentrations) (n = 4). (C) An ELISA repeated on a separate microtiter plate with lower L-Mtd protein concentrations avoids saturation of HRP activity, and demonstrates the high affinity binding by L-Mtd for lysozyme. Error bars in A, B and C depict standard deviation (n = 4). (D) Binding experiments using surface plasmon resonance imaging (SPRI) to measure the affinity of L-Mtd for lysozyme or BSA (negative control). This assay measures the percent change in reflectivity as L-Mtd binds to lysozyme (solid line) or BSA (dotted line) conjugated to the gold layer (solid line). In the table, the rate and dissociation constants were calculated by a least squares fit to the SPRI data with the standard deviation indicated in parentheses (n = 6, single experiment shown).