Figure 2. Reactivity depends on the structural properties of the assembly.

(A) Schematic of the covalently tethered complex. The SpyCatcher-SpyTag complex covalently links the kinase with its substrate. We varied the length of the linker that connects the substrate to SpyCatcher from 2 to 14 residues and measured the unimolecular rate constant (k_intra). (B) Plot of k_intra vs. number of residues. The secondary y-axis shows the effective molarity for each complex, determined using the bimolecular rate constant from the untethered reaction (Figure 3A). Error bars represent the standard error of k_intra obtained from the fit of V_obs vs [tethered complex] as described in Figure S4.