Molecular recognition

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Crystal structure of a short peptide L-Lys-D-Ala-D-Ala (bacterial cell wall precursor) bound to the antibiotic vancomycin through hydrogen bonds reported by Knox and Pratt in Antimicrob. Agents. Chemother., 1990 1342-1347

Crystal structure of two isophthalic acids bound to a host molecule through hydrogen bonds reported by Moore and coworkers in Chem. Commun., 1998, 1313-1314.

Scheme of dynamic molecular recognition. The top shows the case of sodium; this type is a 1:1 type sandwich complex. The bottom is the case of potassium; 2:2 type and 3:2 type complexes were synthesized.

The term molecular recognition refers to the specific interaction between two or more molecules or supermolecules through noncovalent bonding such as including hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-pi interactions, and/or electrostatic effects.[1] The host and guest involved in molecular recognition exhibit molecular complementarity.^[1]

1 Biological systems
2 Supramolecular systems
3 Static vs. dynamic
4 External links

[edit] Biological systems

Molecular recognition plays an important role in biological systems and is observed in between receptor-ligand, antigen-antibody, DNA-protein, sugar-lectin, RNA-ribosome, etc. An important example of molecular recognition is the antibiotic vancomycin that selectively binds with the peptides with terminal D-alanyl-D-alanine in bacterial cells through five hydrogen bonds. The vancomycin is lethal to the bacteria since once it has bound to these particular peptides they are unable to be used to construct the bacteria’s cell wall.

[edit] Supramolecular systems

Chemists have demonstrated that artificial supramolecular systems can be designed that exhibit molecular recognition. One of the earliest examples of such an system are crown ethers which were selectively bind specific cations. However a number of artificial systems have since been established.

[edit] Static vs. dynamic

Molecular recognition can be subdivided into static molecular recognition and dynamic molecular recognition. Static molecular recognition is likened to the interaction between a key and a keyhole; it is a 1:1 type complexation reaction between a host molecule and a guest molecule. To achieve advanced static molecular recognition, it is necessary to make recognition sites that are specific for guest molecules. Dynamic molecular recognition is a molecular recognition reaction that dynamically changes the equilibrium to an n:m type host-guest complex by a recognition guest molecule (see figure). There are some equivalents by the combination of host molecules. Both static molecular recognition and dynamic molecular recognition by metal ions are observed in the case of molecular recognition between crown ether complex and alkali metal ion. Dynamic molecular recognition appearing in supermolecules is essential for designing highly functional chemical sensors and molecular devices. The quest for understanding this principle and its functions is now an important issue.