Binding time, definition

This technique was employed to study the binding dynamics of Pyronine Y (31) and B (32) with /)-CD/ s The theoretical background for this particular system has been discussed with the description of the technique above. Separate analysis of the individual correlation curves obtained was difficult since the diffusion time for the complex could not be determined directly because, even at the highest concentration of CD employed, about 20% of the guest molecules were still free in solution. The curves were therefore analyzed using global analysis to obtain the dissociation rate constant for the 1 1 complex (Table 12). The association rate constant was then calculated from the definition of the equilibrium constant. 

The appropriate definition of nonspecific binding is essential prior to characterization of the kinetic and equilibrium properties of the binding interaction. As a rule, nonspecific binding can be defined using a concentration of the unlabelled ligand that is 100 times its Ka value for the sites of interest. Failure to appropriately define nonspecific binding will invalidate the determination of the binding parameters. 

At this time there is no definitive evidence concerning either the identity of the subunits or the groups involved in their interaction. Since it is possible to observe the dissociation of urease in four discrete steps to (8n), (4n), (2n), and (n) subunits, it seems likely that at least four types of binding arrangements are present. Since the dissociations are symmetrical it seems likely that the subunits are identical at least down to 60,000 daltons. 

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