We have analyzed the influence of anion– π interactions to the stability of Sm/LSm assemblies. The side chain of Glu is more likely to be in anion– π interactions than Asp. Phe has the highest occurrence in these interactions than the other two π residues. Among the anion– π residue pairs, Glu-Phe residue pair showed the maximum number of anion– π . We have found hot-spot residues forming anion– π interactions, and Glu-Phe is the most common hot-spot interacting pair. The significant numbers of anion– π interacting residues identified in the dataset were involved in the formation of multiple anion– π interactions. More than half of the residues involved in these interactions are evolutionarily conserved. The anion– π interaction energies are distance and orientation dependent. It was found that anion– π interactions showed energy less than −15 kcal mol −1 , and most of them have energy in the range −2 to −9 kcal mol −1 . Solvent accessibility pattern of Sm/LSm proteins reveals that all of the interacting residues are preferred to be in buried regions. Most of the interacting residues preferred to be in strand. A significant percentage of anion– π interacting residues are located as stabilization centers and thus might provide additional stability to these proteins. The simultaneous interaction of anions and cations on different faces of the same π –system has been observed. On the whole, the results presented in this work will be very useful for understanding the contribution of anion– π interaction to the stability of Sm/LSm proteins.
Graphical Abstract