Molecular recognition is the specific interaction of one molecule with another by means of noncovalent bonds and hydrophobic effects. Molecular recognition can lead to the formation of a stable or transient complex between the two molecules or can lead to more complex interactions that result in associated allostery, catalysis, or even assembly of molecular machines. The interacting molecular pair can vary widely in size and complexity, from small molecules or even metal ions, to large proteins, nucleic acids, lipid assemblies, and carbohydrates. Molecular recognition is the most fundamental process underpinning life. Virtually every cellular activity can be viewed as a spatially and temporally ordered series of molecular recognition steps involving two or more molecules at each step.
Over the years a variety of models have been proposed to explain molecular recognition from the most fundamental level to the highest level of complexity. These models include, for small molecules, stereochemical fit among others, and for biological molecules, the lock and key, induced fit, conformational selection and coupled binding and folding. Recently very detailed computational models are being explored that probe shape, hydrogen bonding, and charge complementarity. Given the recent advances in high level models and in experimental and computational techniques that identify and probe molecular recognition events, it is time for an update in this rapidly advancing area.