Multi-point interactions

Mozhaev VV, Melik-Nubarov NS, Sergeeva MV et al. (1990) Strategy for stabilising enzymes. I. Increasing stabdity of enzymes via their multi-point interaction with a support. Biocatalysis 3 179-187... 

This effect can be explained with a reversible adsorption of resin molecules to the freshly provided surfaces of silica particles produced by shearing down the cluster structure of the N20 network. The re-formation of the netwoik requires at least a partial desorption of the resin molecules which is a slow and time-consuming process due to the multi-point interaction of the resin chains with the silica surface [12]. 

Multi-point Interaction with Real and Virtual Objects... 

We also revealed that when phenylboronic acid is introduced to the secondary hydroxyl sites of y-CD (receptor 6), the complex of receptor 6 with fluorescent sensor 4 exhibits glucose selectivity in water due to multi-point interaction (Figure 13.7b). Fluorescent sensor 4, when used alone, is a selective fructose sensor. As illustrated by these examples, supramolecular CD complexes have great appeal in that the... 

The multi-point interaction of an adsorbed protein can be expressed as the characteristic charge, v, of the protein. 

Fig. 26. Cooperative closed dimer and trimer featuring multi-point binding interactions.

It is important to select stoichiometric co-reductants or co-oxidants for the reversible cycle of a catalyst. A metallic co-reductant is ultimately converted to the corresponding metal salt in a higher oxidation state, which may work as a Lewis acid. Taking these interactions into account, the requisite catalytic system can be attained through multi-component interactions. Stereoselectivity should also be controlled, from synthetic points of view. The stereoselective and/or stereospecific transformations depend on the intermediary structure. The potential interaction and structural control permit efficient and selective methods in synthetic radical reactions. This chapter describes the construction of the catalytic system for one-electron reduction reactions represented by the pinacol coupling reaction. 

It was pointed out over 60 years ago that the recognition of a chiral (or, as subsequently realized, a prochiral) carbon by an enzyme implies that at least three of the groups surrounding the carbon atom must interact with the enzyme. This is the multi-point attachment theory.4 If only two of the groups interact, the other two may be interchanged without affecting the binding of the substrate (structures 8.9). 

Enzymes are capable of the kind of selectivity and rate enhancements discussed above because their active sites exhibit a number of distinctive features compared to the active sites employed by soluble transition metal complexes and solid state catalysts multi-point contact with the substrate, which is very hard to engineer in a synthetic catalyst the structural flexibility to undergo collective and rapid changes in structure to facilitate catalysis of a reaction and a unique ability to combine apparently incompatible features in catalysis, such as simultaneous acid and base catalysis and hydrophobic/hydrophilic interactions [62,63]. These points are discussed in more detail in the following sections. 

Confusion often arises due to misinterpretation of the term interaction within the conceptional framework of the three-point rule. It is important to understand that in this particular context interaction refers to intermolecular physical forces and their steric implication rather than to specific spatial relationships between substructure elements in the SO and SA entities. This distinction is crucial as intermolecular forces, depending on their physical nature, may be of single-point or of multi-point quality. For example, forces acting exclusively between specific... 

In order to understand HDS reactions, it is important to define the ways in which thiophenes are bonded to metal centers on catalytic surfaces. A number of modes in which T interacts with surfaces have been proposed, the most important ones being the one-point adsorption , that is, a strong interaction between the S atom and a vacancy on the surface, and the multi-point adsorption involving the S atom plus one or both of the C=C bonds in a delocalized rr-bonding. While it is difficult to experimentally obtain detailed information on the bonding of thiophenes to surface sites, several coordination modes of thiophenes have been authenticated in metal complexes (Figure 2). 

Physico-chemical data are usually treated as point values in design. This ignores the uncertainty in the data, and the fact that different products may have to be produced in the future. This is exacerbated by the complexity of physico-chemical processes involving multi-phase, multi-particulate and multi-component systems, with multi-level interactions within them. 

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