Recognition process

The weak intemiolecular forces that are principally involved in stabilizing receptor-substrate interactions and involved in molecular recognition processes (16) are summarized in Table 2. Examples are shown in Figure 1. 

Most effective differentiation of the receptor between substrates will occur when multiple interactions are involved in the recognition process. The more binding regions (contact area) present, the stronger and more selective will be the recognition (17). This is the case for receptor molecules that contain intramolecular cavities, clefts or pockets into which the substrate may fit (Fig. 1). 

Substrates involved in molecular recognition may feature a particular shape, size, state of charge, chemical affinity or optical specification (19,30,33—36). In general most of these parameters share. Nevertheless there may be dominating features of a certain substrate molecule to be used by a complementary receptor in the recognition process (9). 

Dmg receptors are chemical entities which are typically, but not exclusively, small molecules that interact with cellular components, frequently at the plasma membrane level (1,2). There are many types of receptors heat, light, immune, hormone, ion channel, toxin, and vims are but a few that can excite a cell. The receptor concept can be appHed generally to signal recognition processes where a chemical or physical signal is recognized. This recognition is translated into response (Fig. 3) and the process can be seen as a flow of information. 

The use of a polymeric support also affords a unique opportunity to control independently the variables that may affect the chiral recognition process, which is hard to achieve with silica. For example, the type and number of reactive sites can be easily adjusted with a polymer support. We recently reported an extensive study of the... 

A 1 1 mixture of thiols (7 and 2), on treatment with oxygen in the presence of a catalytic amount of Et3N, gives one unsymmetrical (4) and two symmetrical disulfides (3 and 5) (Eq. 4). As a measure of the degree of the recognition between 7 and 2 in the oxidation, the selectivity (r) is employed which is represented by the logarithmic ratio of the yield of 4 to twice that of 3 (Eq. 5). The r is so defined as to become zero when oxidation yields the three disulfides in a 1 2 1 ratio. In the present case, the recognition process is followed by covalent bond formation. 

Potentiometry (discussed in Chapter 5), which is of great practical importance, is a static (zero current) technique in which the information about the sample composition is obtained from measurement of the potential established across a membrane. Different types of membrane materials, possessing different ion-recognition processes, have been developed to impart high selectivity. The resulting potentiometric probes have thus been widely used for several decades for direct monitoring of ionic species such as protons or calcium, fluoride, and potassium ions in complex samples. 

FIGURE 5-11 The recognition process occurring at the TDMAC/PVC membrane/sample interface used for measurements of heparin. (Reproduced with permission from reference 26.)... 

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

Levitzki A (2000) Protein Tyrosine Kinase Inhibitors as Therapeutic Agents. 211 1-15 Li G, Gouzy M-F, Fuhrhop J-H (2002) Recognition Processes with Amphiphilic Carbohydrates in Water. 218 133-158 Li X, see Paldus J (1999) 203 1-20... 

Compounds 23 and 29 were synthesized in three steps from 8 and 25 respectively. These molecules showed no inducing effect, indicating that the hydroxyl in C-4 participates to the recognition process (or that the modified molecules could not enter the bacteria). 

This has been exploited in the elegant work of Alivisatos etal. (182) and Mirkin and co-workers (168,183-185) who have used DNA-recognition processes to organize Au nanoparticles into structured assemblies. The... 

In biological systems one of the primary modes of molecular recognition processes occurs via H-bond formation. Research concerning design and synthesis of molecular components that can self-assemble via H-bonding interactions has been reported [90,155]. 

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