Influence of kinetic barriers on the structures of non-covalently bonded states

The dissociation of two similar bimolecular complexes, of comparable thermo dynamic stabilities, but different kinetic stabilities, is considered. Rela tive to the complex with the lower kinetic barrier to dissociation, it is c oncluded from proton NMR data that the complex with the higher kinetic barr ier to dissociation has, at a defined point, a tighter interface and a less dynamic structure. The work illustrates how high kinetic barriers to disso ciation of non-covalently bonded states can improve bonding at parts of the non-covalently bonded interface. The conclusions drawn should be of genera l relevance to the non-covalent complexes that are involved in biological f unctions.