Nonpolar binding cavity

The relative specificity that laccases have for bulky aromatic (poly) phenols and amines is due not only to the H-bond Network. The type 1 site associated with these H-bonds lies at the base of a shallow cavity that is lined with nonpolar side chains, or the nonpolar aliphatic carbon skeleton of a polar one, for example, Q and K. The binding cavities of two laccases (superimposed) are shown in Figure 9(b). As discussed below, those MCOs that exhibit a strong specificity for Fe + as substrate the ferroxidases - have a substrate binding site that differs in two respects from the laccase one the ferroxidase site is spatially more constrained and it... 

Morton, A., Baase, W. A., Matthews, B. W. Energetic origins of specificity of ligand binding in an interior nonpolar cavity of T4 lysozyme. Biochemistry 34 (1995) 8564-8575. 

A for K, Rb , and Cs and 5.5—7.4 A for Na and Li . It is understandable that the cavity fits in with K. Carbonyl groups are distributed along the inside wall of the cavity which is necessarily polar. Aliphatic side dtains form the outside wall of the bracelet whidi is necessarily nonpolar. Valinomycin binds K in the hydro-0ulic interior of the cavity and transports the ion across the lipid bilayer of the cell... 

These torus-shaped28 hosts can accommodate many sorts of organic molecules that can reside within the nonpolar cavity. The strength of this noncovalent interaction is directly related to the position of the equilibrium for complex formation. This is evaluated by a binding constant (A)29 that may be measured in a variety of different ways, e.g., spectrofluorometric methods based on competition experiments.30 Recently, ICD has also been used to assess the binding constants of carbene-forming 3//-diazirine CyD ICs.17... 

Potassium acetate can be dissolved in a nonpolar solvent such as benzene if [18]-crown-6 is added to the solution. The crown ether binds potassium in its cavity, and the nonpolar crown ether-potassium complex dissolves in benzene, along with the acetate ion, to maintain electrical neutrality. The crown ether is acting as a phase-transfer catalyst—it is bringing a reactant into the phase where it is needed. Because acetate is not solvated in the nonpolar solvent, it is a much better nucleophile than it would be in a... 

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