Lock and key principle

Behr, J.-P. (1994) The Lock-and-Key Principle The State of the Art-100 Years, John Wiley Sons, Inc., New York. 

Weissbuch I, Popovitz-Biro R, Leiserowitz L, Lahav M (1994) In Behr J-P (ed) Perspectives in supramolecular chemistry, vol 1 The state of the art—100 years of the lock-and-key principle. Wiley, New York, p 173... 

Fig. 4.10. Illustration of the lock-and-key principle for the complexation of spherical entities.

After reactants have adsorbed within the zeolite mouth and have diffused towards the actives sites, they must react. Selective adsorption depends on the local topology of the active site, its immediate neighborhood, and on size and shape of the reactant. One may say that a similar behavior as the lock and key principle of molecular recognition known from biochemistry applies. In this sense zeolites can be viewed as analog of enzymatic catalysts. This adsorption selectivity of the reactants to the active sites favors preferential reaction pathways. 

Molecular Recognition as the Basis of Supramolecular Chemistry The origin of supramolecular chemistry lies in molecular recognition chemistry, which studies how molecules recognize their partner. It is based on the lock and key principle. 

The recognition of one molecule out of a crowd of many other molecules requires distinction of certain molecular attributes, such as size, polarity, hydrogen bond pattern, chirality, or other physicochemical properties. If several attributes can be checked simultaneously, recognition becomes more selective. Recognition between an enzyme and a substrate was described first by Emil Fischer as the well-known lock and key principle [2], Molecular recognition between complementary DNA strands [3] or protein ligand interactions [4] is very important for the molecular function of living systems. 

The first category comprises a few theories. Kistiakowsky [6] stated that the olfactory response may be set off by a system of reactions that are catalysed by enzymes. A smelling molecule would inhibit the action of one or more of the enzymes. Another theory is that the primary factor determining the odour of a substance might be the overall geometric shape of the molecule. Amoore [7] proposed the stereochemical theory, which provides a mechanism based on a lock-and-key principle. 

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