| 摘要： |
C-H center dot center dot center dot pi and N-H center dot center dot center dot pi interactions can have an important contribution for protein stability. However, direct measurements of these interactions in proteins are rarely reported. In this work, we combined the mutant cycle experiments and molecular dynamics (MD) simulations to characterize C-H center dot center dot center dot pi and N-H center dot center dot center dot pi interactions and their cooperativity in two model proteins. It is shown that the average C-H center dot center dot center dot pi interaction per residue pair is similar to -0.5 kcal/mol while the N-H center dot center dot center dot pi interaction is slightly stronger. The triple mutant box measurement indicates that N-H center dot center dot center dot pi center dot center dot center dot C-H center dot center dot center dot pi and C-H center dot center dot center dot pi center dot center dot center dot C-H center dot center dot center dot pi can have a positive or negative cooperativity. MD simulations suggest that the cooperativity, depending on the local environment of the interactions, mainly arises from the geometric rearrangement when the nearby interaction is perturbed. |
