Wasserstoffbrückenbindungen

Wasserstoffbrücke (hydrogen bond) is a type of non-covalent interaction that forms when a hydrogen atom covalently bonded to an electronegative atom, such as oxygen or nitrogen, experiences an attractive interaction with another electronegative atom bearing a lone pair. The bond is directional and weaker than a covalent bond, typically ranging from about 4 to 30 kilojoules per mole, depending on the environment. Hydrogen bonds are crucial for many physical properties and biological processes.

In water, each molecule can form multiple hydrogen bonds, creating a dynamic network that contributes to water’s high boiling point, surface tension, and the structure of ice. In biomolecules, hydrogen bonds stabilize secondary structures such as alpha helices and beta sheets in proteins, base pairing in nucleic acids (A–T and G–C), and the folding of RNA. They also influence enzyme–substrate recognition and protein–ligand interactions. Hydrogen bonds are essential for the specificity and stability of molecular recognition in cells.

Donor and acceptor: a hydrogen bond involves a donor (a hydrogen attached to an electronegative atom) and an acceptor (an electronegative atom with a lone pair). Common donors are O–H and N–H; common acceptors are O and N, with variations in strength.

Measurement and variability: hydrogen bonds are non-covalent and dynamic, inferred from spectroscopy, thermodynamics, and structural data. Their strength and number vary with temperature, pressure, and solvent. The concept, popularized in the 1930s by Linus Pauling, remains a central part of understanding chemistry and biology.