Molecular recognition types

Fixation substrate functions depend largely on molecular level structure and properties such as chemical and stereospecific structure, the structure and property of supramolecular materials, and macroscopic properties like high porosity. In addition to the progress already made in both s)mthesis of functional polymers such as stimuli-responsive and molecular recognition types and development of composite manufacturing methods, if morphological characteristics can be utilized, enzyme reactions will be possible anytime they are needed. 

According to these basic concepts, molecular recognition implies complementary lock-and-key type fit between molecules. The lock is the molecular receptor and the key is the substrate that is recognised and selected to give a defined receptor—substrate complex, a coordination compound or a supermolecule. Hence molecular recognition is one of the three main pillars, fixation, coordination, and recognition, that lay foundation of what is now called supramolecular chemistry (8—11). 

Fig. 3. Schematic approach illustrating amplifica tion of molecular recognition effects of (a) matched rigid, (b) mismatched rigid, and (c) flexible type of...

Microporous inorganic materials dominated historically by the 2eohtes and alumosilicates, and the great variety of more recent nonoxide and coordination framework materials should also be mentioned here (171—174) but not discussed in detail. This type of molecular recognition is usually known as molecular sieving. 

The problem of molecular recognition has attracted biologically oriented chemists since Emil Fischer s lock-and-key theory l0). Within the last two decades, many model compounds have been developed micelle-forming detergents11, modified cyclodextrins 12), many kinds of crown-type compounds13) including podands, coronands, cryptands, and spherands. Very extensive studies using these compounds have, however, not been made from a point of view of whether or not shape similarity affects the discrimination. 

Crystalline 1 1 complex formation can be regarded as molecular recognition in the process of crystallization. Since the formation of a new type of the crystalline 1 1 complex depends on the shapes of R7 and R8 35), the influence of the spatial relationship between R7 and R8 on the complex formation was investigated. 

Additional clathrate inclusions of this particular type of functional group free hosts have been studied by Toda and coworkers (see Chapter 3 in Vol. 140 of this series, Molecular Inclusion and Molecular Recognition — Clathrates I ). 

We are attempting to understand the biological significance of the large variations in frequency of putative LDRs, whether between different types of bacteria or archaea, or between pro- and eukaryota. We have carefully studied the literature of more than 90 example proteins selected from our disordered protein databases and found reports on the functions of most of the disordered regions (Dunker et al., 2002). The observed functions and the number of examples in each functional class are given in Table VI. As indicated, four major functional classes were found molecular recognition, molecular assembly or disassembly, protein modification, and entropic chains. 

Thus, the concept and manifestation of molecular recognition mediated supramolecular self-assembly of small chemical units, be it an ABn type building block or a dendrimer molecule, have proved to be vital factors in bridging the gap between small molecules and novel new-age materials. 

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