Fig. 3.

Noise affects SELEX dynamics. We fix the experimental parameters, the initial Gaussian distribution $N\left(-\mathrm{4,0.4}\right)$ and the added noise of only 20 additional ligands initially present between $K_D={10}^{-10}M$ and $5\times {10}^{-8}M$. Two different Monte Carlo simulations from these identical initial conditions show dynamics of selection under random loss of the 20 strongest binders (blue triangles), versus dynamics when only two of those strong binders with affinities between ${10}^{-10}$ and ${10}^{-9}M$ are selected (red dots). In the latter case, these two high-affinity binders completely dominate the distribution from cycle 12 on and outcompete the remaining ligands with low affinities ($K_D>{10}^{-7}M$).