Fig. 3: The optimal design of the HMSD-based catalyst experiences only moderate competitive product inhibition and achieves high turnover.

a, The reacted monomer concentration [M₁L] in a system with 10 nM N₃, 10 nM M₁L, 1 nM T and an initial non-fluorescent pool of products M₁N₃ at a range of concentrations \({[{M}_{1}{N}_{3}]}_{0}\). The condition 6t/8h, considered as optimal, is highlighted in red. b, The initial TOF at different \({[{M}_{1}{N}_{3}]}_{0}\) conditions for 6t/8h, 6t/9h and 6t/10h, obtained from the kinetics depicted in a. The symbols are centred on the best fit of the TOF to a single trajectory, with the height indicating a 95% confidence interval on that fit. Although 6t/9h has a higher TOF in the absence of [M₁N₃], 6t/8h combines rapid growth with a higher resistance to rate reduction at high \({[{M}_{1}{N}_{3}]}_{0}\). c, The turnover of M₁L as inferred from fluorescence data, in experiments with 100 nM M₁L, 100 nM N₃ and variable concentrations of the template \({[{T}_{13}]}_{0}\) (6t/8h). A large proportion of M₁L is observed to react, even for a concentration of \({[{T}_{13}]}_{0}\) 400 times lower than the number of monomers, reaching turnovers above 20 products per template. The template-free leak reactions are essentially negligible (0.32 ± 0.06 M⁻¹ s⁻¹) even compared with the lowest template concentration regimes. d, The initial rates of reactions from c and an additional set of replica experiments (Supplementary Note 7.2), as a function of \({[{T}_{13}]}_{0}\). The symbols are centred on the best fit of the rate to a single trajectory, with the error bars giving a 95% confidence interval on that fit. The red line is the linear fit of the system TOF (3.6 ± 0.3 h⁻¹) to the 11 independent kinetic measurements, the red dashed line is the 95% confidence interval of that fit and the black dashed line is the untemplated rate for monomers at 100 nM = 0.012 ± 0.002 nM h⁻¹.