Figure 3.

Cyclic voltammetry was used to measure the rate of the reaction of a cutinase−SH2 fusion protein with the immobilized substrate. Representative cyclic voltammograms for a surface that presents substrate together with phosphorylated peptide ligand (pY) for the SH2 domain (A) and for a surface that presents the substrate with an inactive form of the ligand (Y) (B). (C) The density of hydroquinone product on the monolayer was measured during the reaction for pY (●) and Y (△) presenting surfaces, showing an approximately 30-fold greater initial rate for the former. (D) An analogous experiment using cutinase—but without the SH2 domain—reveals similar rates for the interfacial reaction on the two monolayers, demonstrating that the rate enhancement is only due to binding between the SH2 domain and the pY ligand.