Antibody combining site

The palytoxin-anti-palytoxin reaction is unique in that its binding increases with increasing temperature (Figure 4). The apparent association constant of the palytoxin to anti-palytoxin was 4.9 x 10 M at 0 C and 1.1 x 10 M" at 35 C, suggesting that H2O must be displaced from some of palytoxin s epitopes before they can bind to their antibody combining sites. 

The antibody-catalyzed Diels-Alder reaction developed by Schultz utilized a Diel-Alderase enzyme-like catalyst evolved from an antibody-combining site (Eq. 12.13). The idea is that the generation of antibodies to a structure that mimics the transition state for the Diels-Alder reaction should result in an antibody-combining site that lowers the entropy of activation by binding both the diene and dienophile in a reactive conformation. 

Competitive immunoassay relies on tne competition between labelled and unlahelled antigens for a fixed and limited number of antibody-combining sites. 

The bait and switch tactic clearly illustrates that antibodies are capable of a coulombic response that is potentially orthogonal to the use of transition state analogues in engendering catalysis. By variations in the hapten employed, it is possible to fashion antibody combining sites that contain individual residues to deliver intricate mechanisms of catalysis. 

Fig. 38 The mechanism by which an essential Lys residue in the antibody combining site is trapped using the 1,3-diketone [117] to form the covalently linked vinylogous...

Another possible explanation for the limitations of catalytic antibodies raised against TSA can be found in the different accessibility of the active site. In the case of natural enzymes, it is that their catalytic machinery and bound substrates are often buried. This feature isolates from the solvent the reactive functionalities that mediate chemical transformations. On the contrary, in antibody catalysis, the moieties of the bound haptens that mimic the TS are often positioned near the entrance of the antibody-combining site. This disparity in the overall architecture of natural enzymes and catalytic antibodies is undoubtedly a factor in the lower catalytic... 

Fig. 5 The crystal structure of the antibody-octapeptide complex, with STD-NMR intensities mapped onto the bound peptide. Residues of the antibody combining site are shown in purple, with selected residues labeled, and the direction of the backbone indicated in ribbon representation. Residues of the peptide are labeled in italics. Heavy atoms of the peptide are shown in gray, while the default color for hydrogen atoms is white. Observed STD-NMR intensities are mapped onto hydrogen atoms of the peptide by color, with red indicating 50-100% enhancement, orange 30-50% enhancement, a.nd yellow < 30% enhancement. Protons that are definitely not enhanced are shown in black those for which no enhancement could be determined (due to interference by other resonances, or not observable in the ID spectrum) remain white. Reproduced with permission from [100]. 2004 Elsevier Science...

Antibodies Affinity labeling of antibody combining sites as illustrated by anti-dinitrophenyl antibodies, 46, 479 p-azoben-zenearsonate antibody, 46, 492 affinity cross-linking of heavy and light chains, 46, 501 bivalent affinity labeling haptens in the formation of model immune complexes, 46, 505 DNP-based diazoketones and azides, 46, 508 labeling of antilactose antibody, 46, 516. 

Porter, R.R., The structure of the heavy chain of immunoglobulin and its relevance to the nature of the antibody-combining site the Second CIBA Medal Lecture. Biochem 1,1967.105(2) 417-26. 

Figure 3.8. Basic Four—polypeptide chain structural unit of an immunoglobulin. <- - represents the antibody-combining sites.(From Butler 1969. Reprinted with permission of the American Dairy Science Association.)...

David R. Bundle (Canada) Oligosaccharide-protein interactions. Studies of antibody-combining sites by competitive bonding, sequence analysis and X-ray crystallography... 

---