Chapter 2 Non-covalent forces of importance in biochemistry

Abstract

Publisher Summary The nature of non-covalent forces makes them important in biological function because they are specific without conferring as much rigidity as covalent forces. Covalent forces are those quantum mechanical forces, which determine the nature of electron pair chemical bonding. Non-covalent forces, on the other hand, do not involve electron pairing effects. These non-covalent forces play an essential role in determining the shape of all molecules and the macromolecules, which are important in biology, are no exception. The base stacking and hydrogen bonding in the DNA double helix, the hydrogen bonding in the peptide α helix, and the U shape of prostaglandin molecules are examples where non-covalent forces determine shape. The specificity in intermolecular association between proteins and nucleic acids and between enzymes and their inhibitor is also a result of the nature of these non-covalent forces. The most important attractive non-covalent forces for biological association in aqueous solution are electrostatic, dispersion, and hydrophobic. Electrostatic interactions are more important in providing specificity than in contributing to the overall thermodynamic driving force for association. It is likely that dispersion is important and hydrophobic terms essential in most protein–ligand interactions.