The Effect of Nonnative Interactions on the Energy Landscapes of Frustrated Model Proteins

The 46- and 69-residue BLN model proteins both exhibit frustrated folding to β-barrel structures. We study the effect of varying the strength of nonnative interactions on the corresponding energy landscapes by introducing a parameter , which scales the potential between the BLN (=1) and Gō-like (=0) limits. We study the effect of varying on the efficiency of global optimisation using basin-hopping and genetic algorithms. We also construct disconnectivity graphs for these proteins at selected values of . Both methods indicate that the potential energy surface is frustrated for the original BLN potential but rapidly becomes less frustrated as decreases. For values of ≤0.9, the energy landscape is funnelled. The fastest mean first encounter time for the global minimum does not correspond to the Gō model: instead, we observe a minimum when the favourable nonnative interactions are still present to a small degree.