Receptor binding cavity

C-2 hydroxyl acts as a H-bond acceptor, with restricted space in the receptor binding cavity around this position. ... 

A distance geometry approach using a three-dimensional structure-directed QSAR method (REMOTEDISC)was employed to analyze the inhibition of [ H]diazepam binding by 29 benzodiazepines (115). The results of the method, which uses three-dimensional structure, conformational energies, and atom-based physiochemical properties to model the receptor binding cavity were based on Equation 5.12. 

OH-D3(ca. 1/500 relative to la,25-(OH)2D3) implies perlups an unfavorable steric interaction between the transposed exocyclic methylene unit of the latter and the receptor binding cavity, which reduction to methyl (giving 25-OH-DHT3 (lOg) ca. 1/100 relative to la,25-(OH)2D3) appears to alleviate measurably. 

The size and shape of the binding cavity that they define and their rigidity or flexibility are determined by the nature of the structural subunits making up the branches of the graphical representations. Their overall shape and appearance has also led to the coining of a number of so-called trivial names that refer to a particular aspect of the structure. Proposals have been made to name and define different types of macrocyclic ligands and molecular receptors [2.12]. Without being ex-... 

Sessler has combined amidopyrroles with the ferrocene moiety has resulted in new macrocyclic anion receptors in which the anion-binding cavity could be adjusted in size by variation of the bridging alkyl chain to allow selectivity of this class of receptor to be fine-tuned (Figure 26).25... 

Figure 15.8 Schematic representation of the proposed mechanisms for mode of action of OBPs in the perireceptor events. Pheromone (or other semiochemicals) enters the sensillar lymph through cuticular openings (pore tubules), is solubilized by an odorant-binding protein, transported to the olfactory receptors, and protected from degrading enzymes. Interaction with negatively charged sites at the surface of the dendrites triggers a conformational change that leads to the formation of a C-terminal a-helix. The insertion of this helix into the binding cavity ejects the pheromone to the olfactory receptors.

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