A noncovalent bond is a type of chemical bond, typically between macromolecules, that does not involve the sharing of pairs of electrons, but rather involves more dispersed variations of electromagnetic interactions. The noncovalent bond is the dominant type of bond between supermolecules in supermolecular chemistry. Noncovalent bonds are critical in maintaining the three-dimensional structure of large molecules, such as proteins and nucleic acids, and are involved in many biological processes in which large molecules bind specifically but transiently to one another. The energy released in the formation of noncovalent bonds is on the order of 1-5 kcal per mol. Noncovalent bonds – Molecular Cell Biology (textbook), Lodish, Berk, Zipursky, Matsudaira, Baltimore, Darnell. There are four main types of non-covalent bonds: hydrogen bonding, ionic interactions, Van der Waals interactions, and hydrophobic bonds. Examples of noncovalent bonds include: those binding interactions which hold the two strands DNA in the DNA double helix together, those which fold polypeptides into such secondary structures as the alpha helix and the beta conformation, those which enable enzymes to bind to their substrate, and those which enable antibodies to bind to their antigen.