Multiple binding specificities

Boulanger, Y. Schreier, S. Leitch, L. C. Smith, I. C. R, Multiple binding sites for local anesthetics in membranes Characterization of the sites and their equilibria by deuterium NMR of specifically deuterated procaine and tetracaine, Can. J. Biochem. 58, 986-995 (1980). 

B0 and B, are the amounts bound initially (at 1 = 0) and at specific times (t) after initiating dissociation. A plot of log,/l, against l is linear with a slope of -k, k may thus be estimated directly from the slope of this plot or may be obtained by nonlinear least-squares curve fitting to Eq. (5.12). It is always desirable to plot log,/) , against l to detect any nonlinearity that might reflect either the presence of multiple binding sites or the existence of more than one occupied state of the receptor. 

In the case of multiple binding sites or if the ligand-receptor complex isomerizes, the onset and offset curves will be multiexponential. It is generally assumed that nonspecific binding will occur rapidly, and this should certainly be so for simple entrapment in a membrane or cell pellet. If, however, specific binding is very rapid or nonspecific binding particularly slow (possibly... 

Antibodies typically are able to recognize peptide sequences as small as 5-6 amino acids in length. For instance, IgE auto-antibodies were found to have clinical significance in multiple sclerosis by binding specifically to short 5- and 6-amino acid epitopes on the surface of myelin proteins (Mikol et al., 2006). 

Several predictions of this model have been experimentally supported, including the estimated heme-heme distance, and the protection of various (charged) groups on cytochrome c and ccp. However, as already noted, other theoretical models have suggested that multiple binding sites are possible within the cyt c ccp complex. The available spectroscopic and crystallographic data, reviewed in this section, tend to support a multisite model, rather than a highly specific lock and key structural model. 

Recently reported synthetic macrocyclic molecules with hydrophilic cavities containing multiple binding atoms and with hydrophobic exteriors make possible controlled studies of selective cation complexa-tion. Certain of these cation-ligand systems appear to mimic biological systems which have remarkable element specificities. Such cation-ligand systems may be considered as models for the study of this unusual property of living systems. 

Self, C. H., Dessi, J. L., and Winger, L. A., Ultra-specific immunoassays for small molecules Roles of wash steps and multiple binding formats. Clin. Chem. 42, 1527-1531 (1996). 

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