Conformation-specific antibodies to the alpha chain COOH terminus of hemoglobin A0

Review of conformation-specific affinity purification methods for plasma vitamin K-dependent proteins

There are seven known vitamin K-dependent proteins in blood. These proteins require calcium ion for expressing their full biological activities. Calcium ion also induces conformational changes in this class of proteins. Taking advantage of the ligand induced conformational changes, a number of unique approaches of affinity chromatography have been developed. These methodologies have been very useful tools for both the purification and for understanding the structure-function relationships of this class of proteins. One method is the use of metal ion dependent immunoaffinity chromatography. The antigen can be dissociated from the antibodies with either the removal or addition of calcium ion under physiological conditions. The other method is pseudoaffinity chromatography. This method uses conventional ion-exchange or hydrophobic resin and manipulates the mobilities of the proteins on these resins by the presence or absence of calcium ions. Researchers working with other calcium binding proteins or other proteins that are known to undergo ligand induced conformational changes may benefit from the experience of these unique conformation-specific affinity chromatography approaches.

Intrinsic and extrinsic factors in protein antigenic structure

Recent advances in the preparation of synthetic peptide vaccines and the use of synthetic peptides as probes of antigenic structure and function have led to renewed interest in the prediction of antigenic sites recognized by antibodies and T cells. This review focuses on antibodies. Features intrinsic to the antigen, such as hydrophilicity and mobility, may be useful in the selection of amino acid sequences of the native protein that will elicit antibodies cross-reacting with peptides, or sequences which, as peptides, will be more likely to elicit antibodies cross-reactive with the native protein. Structural mobility may also contribute to protein-protein interactions in general. However, the entire accessible surface of a protein is likely to be detectable by a large enough panel of antibodies. Which of these antibodies are made in any individual depends on factors extrinsic to the antigen molecule, host factors such as self-tolerance, immune response genes, idiotype networks, and the immunoglobulin structural gene repertoire.

Antigenic structures of proteins. Their determination has revealed important aspects of immune recognition and generated strategies for synthetic mimicking of protein binding sites

Studies in this laboratory have resulted in the delineation and synthetic verification of several complete protein antigenic structures that are recognized by antibodies. More recently, for the first time, the full profiles of the sites that are recognized by T cells have been localized and confirmed by synthesis for two proteins, myoglobin and lysozyme. These have thus far constituted the only complete antigenic structures to be determined. The availability of these antigenic structures has enabled us to investigate in detail the molecular and cellular parameters responsible for immune recognition, responses to, and control and regulation of these responses to protein antigens at the molecular and submolecular levels. Moreover, these investigations have afforded general strategies for the synthetic mimicking of not only antigenic sites, but also protein binding sites involved in other biological activities.