(a) Normalized radial distribution function for the number density

*G*(

*r*) in the heterodimer (in black) and homodimer (in grey). The distance

*r* is measured from the dimer center of mass.

*G*(0) represents the number density in the center of the heterodimer or homodimer. Inset: the number density pair correlation function

*g*(

*r*) (circles) computed for the heterodimer. Correlation radius λ is estimated by applying the exponential fit

*g*(

*r*)=

*g*_{0} exp(−(

*r*−

*r*_{0})∕λ) at

*r* > 5 Å (continuous line). The fitting parameters are

*g*_{o} = 0.03 Å

^{−3},

*r*_{0} = 5.3 Å, and λ = 7.3 Å. The pair correlation function

*g*(

*r*) computed excluding adjacent amino acids is shown by squares. For comparison, the parameters of the exponential fit to the homodimer

*g*(

*r*) are very similar (

*g*_{o} = 0.03 Å

^{−3},

*r*_{0} = 5.2 Å, and λ = 7.2 Å). (b) Probability distribution

*P*(

*r*_{1N}) of the distances

*r*_{1N} between the N- and C-terminals of the heterodimer WT peptide. Gaussian function (Eq. 1) shown by the black curve provides an excellent fit to

*P*(

*r*_{1N}). Inset: the peptide segment end-to-end distance

as a function of the number of amino acids in the segment |

*i* −

*j*|. Filled and open circles are for the WT and RND peptides. Linear fits

are shown by thick lines (

*l* = 1.45 Å and 2.19 Å for the WT and RND peptides, respectively). Panels (a, b) suggest that the heterodimer has globule-like properties. (c) Probability

*P*_{c}(

*k*) for amino acid type

*k* to occur in the dimer core: WT peptide (filled circles), RND peptide (open circles). Similarities in

*P*_{c}(

*k*) for the two peptides suggest that spatial distribution of amino acids in the dimer is not affected by sequence reshuffling. All plots are obtained at 360 K.

## PubMed Commons