The aromatic stacking interactions between proteins and their macromolecular ligands.

Aromatic stacking interactions arise from the attractive force between the π-electron clouds in the neighboring aromatic groups. The aromatic stacking is common between proteins and small molecules. The stacking interactions at the interfaces of proteins and other macromolecules are relatively rare. However it contributes to a significant portion of the stabilizing forces. In the proteinprotein complexes, aromatic interactions are involved in the protein oligomerization, such as dimer, trimer and tetramer formation. Also, aromatic residues can bind to nanoparticles through stacking interactions which offer them stronger affinity than other residues. These interactions play crucial roles in proteinnanoparticle conjugation. In the protein-nucleotide complexes, the specific recognitions are realized through stacking interactions between aromatic residues and the bases in the nucleotides. Many nucleoproteins use aromatic stacking to recognize binding site on DNA or RNA. Stacking interactions are involved in the process of mismatch repair, strand separation, deadenylation, degradation and RNA cap binding. They are proved to be important for the stability of complexes. The aromatic stacking is also the underlying reasons of many fatal diseases such as Alzheimer, cancer and cardiovascular diseases. The chemicals that can block the stacking interactions could have potential pharmaceutical values. In this review, we summarize recent finding regarding the functions of aromatic stacking interactions in the protein-macromolecule complexes. Our aim is to understand the mechanisms underlying the stacking-mediated complex formation and facilitate the development of drugs and other bio-products.