Invited Review Hydrogen Bonding: From Small Clusters to Biopolymers

High quality ab initio computations and molecular spectroscopy of small hydrogen-bonded clusters in the vapor phase provide highly accurate data in general agreement with the theory of hydrogen bonds developed in the seventies. Hydrogen bonding is a major force determining energetics and structures of biopolymers. In addition to direct influence through the directionality hydrogen bonds set the stage for the formation of biopolymer structures indirectly since they are the basis of water structure: on the basis of current results hydrophobic interactions are considered equally important or even more relevant than direct hydrogen bonding. A new concept for protein and nucleic acid folding which is based on statistical mechanics allows to study the role of hydrogen bond formation in the nucleation process as well as in later states.