To match the chain simulation model, we used

= 438.0 Å

^{3}, where

*b* = 3.8 Å is the

–

virtual bond length and

= 6 Å is the capture radius for a cation-π contact in the chain model. (A) The IDP's chain length

*n* = 66, with

*k* = 6 (corresponding to the sequences in Fig. 1).

was computed for different

values.

= 32 for the target and

*V* = (600 Å)

^{3} as in the simulations [hence

= 13.1]. Inset: The energy (

) and entropy (

) components of

for

= −3.5. Results in (B–D) are also for

= −3.5. (B) Effects of

*k* and

*V* on binding;

= 32;

= 1/(600 Å)

^{3} is used as a reference IDP concentration. The black curves show

at

for hypothetical sequences with

*k* = 9, 8, 7, 6, 5, 4, and 3 (from top to bottom),

*n* = 66 for

*k*≤6 and

*n* =

for

*k*≥7. The blue curves are for the

*k* = 6 sequences for three IDP concentrations

with

*C* = 0.25, 3.0, and 10.0 (from top to bottom). (C)

for

*k* = 6 sequences at

*C* = 1 on different targets of the same size with different

= 8, 16, 32, 48, 64, and 80 (from left to right; see Text S1 and Fig. S5B). (D)

of the

*k* = 6 sequences at different IDP concentrations

*C* = 10.0, 5.0, 4.0, 3.0, 2.0, 1.0, 0.5, 0.33, and 0.25 (from top to bottom).

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