2021-08-26 06:50 Protein-protein interaction (PPI) is a highly specific physical contact established between two or more protein molecules, which is the result of biochemical events generated by interactions, including electrostatic forces, hydrogen bonds, and Hydrophobic effect. Many are physical contacts of molecular associations between chains that occur in cells or living organisms in a specific biomolecular environment. Proteins rarely work alone because their functions tend to be regulated.