Biological Recognition Processes

The electrostatic potential is well suited for analyzing processes based on the recognition of one molecule by another, as in drug-receptor and enzyme-substrate interactions, because it is through their potentials that the two species first see each other. In recognition processes, the initial step is one in which the receptor or enzyme recognizes that an approaching molecule has 

Dibenzo-p-dioxin (15) is the parent molecule of a large family of derivatives having halogens and other substituents at various positions. These range in toxicity from virtually none (e.g., 15) to very high the latter is exemplified by the notorious 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 16). TCDD is produced as a by-product in the synthesis of the herbicide 2,4,5-trichloro- 

It has been observed that the most toxic dibenzo-p-dioxins are essentially planar and rectangular, with dimensions of approximately 3 x 10 A, and have at least three of the four lateral positions (2, 3, 7, and 8) halogenated, with at least one ring position unsubstituted.Other molecular frameworks besides that of dibenzo-p-dioxin can also meet these structural requirements for high degrees of activity when appropriately halogenated, e.g., dibenzofuran (17), 

In light of the known importance of electrostatic effects in hydrogen bonding, it is not surprising that the molecular electrostatic potential has been used to provide some useful guidelines concerning such interactions. These 

Dashed contours correspond to negative potentials. The positions of the most negative potentials are indicated the values are ( ) - 12.4 ( ) - 7.6. 

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Electrochemical biosensors combine die analytical power of electrochemical techniques with the specificity of biological recognition processes. The aim is to... 

In biological recognition phenomena, protein-protein interactions are of primary importance. In an attempt to mimic these processes, LaBrenz and Kelly [51] synthesized the peptidic host 64. In this receptor, the dibenzofuran template separates the two peptide units by roughly 10 A and allows for the complexation of a guest peptide (65), as depicted in Fig. 21. The complex first forms a three-stranded, antiparallel /J-sheet that is stabilized by hydrogen bonds, electrostatic interactions, and aromatic-aromatic interactions between the dibenzofuran and the benzamide moieties. This complex can further self associate to form more complex structures. This example shows that structurally defined peptide nanostructures can interfere with biological recognition processes and potentially have therapeutic applications. 

Lewisx (SLex, 26).76 The enzyme trans-sialidase transfers sialic acid to 0-3 of the galactose unit.77 Thus, the 3 -deoxy derivatives of the disaccharides would be useful for studying biological recognition processes. 

Another sensor based on a fiber-optic-based spectroelectrochemical probe uses a DNA/ethidium bromide system to take advantage of the biological recognition processes [92]. The concept of immobilizing electrochemical reagents on the end of an optical fibre is a useful addition to the field of bioanalytical sensors. Before this development, optical and electrochemical detection of DNA were performed separately. Optical and electrochemical detection of DNA are suitable for a DNA detection system [93, 94] and these techniques will enable a production of a cheap DNA biosensor with a rapid and quantitative response. 

T. I. Oprea and L. Kurunczi in N. Voiculetz, I. Motoc, and Z. Simon, Eds., Specific Interactions and Biological Recognition Processes, CRC Press, Boca Raton, FL, 1993/pp. 295-326. 

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