Fig. 4: Force-dependent looping rate of helix-heterotetramer.
From: Modulating mechanical stability of heterodimerization between engineered orthogonal helical domains
a An example of the force-clamping procedure to quantify the rate of the formation of the helix-heterotetramer in the linked construct 13-a1a2Lb1b2 at various forces. After jumping from a higher force (~28.1 pN) where the construct is in the unlooped state to a lower force (~2.6 pN), the average looping probability is measured within certain waiting time (Δt = 30 s) in multiple cycles. The looping transition is indicated by a stepwise bead height decrease at ~2.6 pN (blue arrows). The magenta dash lines indicate the bead height difference between looped and unlooped states at 9.6 pN (~70 nm). b Time-dependent looping probability of the construct, P(Δt) at different forces indicated by different colors. The vertical error bars indicate standard errors. Colored lines represent the exponential fitting of the pairing probability \({\mathrm{P}}\left( {\Delta t} \right) = \frac{{k_p}}{{k_p + k_u}}\left( {1 - e^{ - (k_{\mathrm{p}} + k_{\mathrm{u}})\Delta t}} \right)\). Source data are provided in the Source Data file.
