scholarly journals Prediction and conformation by synthesis of two antigenic sites in human haemoglobin by extrapolation from the known antigenic structure of sperm-whale myoglobin

1977 ◽  
Vol 167 (1) ◽  
pp. 275-278 ◽  
Author(s):  
A L Kazim ◽  
M Z Atassi
Keyword(s):  
Sperm Whale ◽  
Antigenic Structure ◽  
Homologous Proteins ◽  
Human Haemoglobin ◽  
Antigenic Sites ◽  
Inductive Effects ◽  
Structural Analogy ◽  
Starting Model ◽  
Sperm Whale Myoglobin

The complete antigenic structure of sperm-whale myoglobin was previously determined in our laboratory. By structural analogy with myoglobin, two regions in human haemoglobin were predicted to comprise antigenic sites. One region was on the alpha-chain [alpha-(15-23)] and the other on the beta-chain [beta-(16-23)]. These two regions were synthesized, purified and characterized, and their immunochemistry was studied. Each peptide was able specifically to bind considerable amounts of haemoglobin antibodies. In a set of homologous proteins, barring any drastic conformational or electrostatic inductive effects exerted by the substitutions, and allowing for obstruction due to subunit interaction, the determination of the antigenic structure of one protein may serve as a useful starting model for the others.

scholarly journals Nearest-neighbour analysis of myoglobin antigenic sites. Nearest-neighbour residues whose replacement can alter the environment of binding-site residue(s) and thus change their characteristics and binding capability

1980 ◽  
Vol 191 (3) ◽  
pp. 673-680 ◽  
Author(s):  
A L Kazim ◽  
M Z Atassi
Keyword(s):  
Binding Capacity ◽  
Antigenic Site ◽  
Sperm Whale ◽  
Antigenic Structure ◽  
Nearest Neighbour ◽  
X Ray ◽  
Antigenic Sites ◽  
Binding Capability ◽  
Sperm Whale Myoglobin ◽  
Neighbour Analysis

By using the known antigenic structure of sperm-whale myoglobin previously determined in this laboratory and the X-ray co-ordinates for the myoglobin molecule, we have calculated the nearest-atom distances between each of the residues of the antigenic sites and all the other amino acids of the myoglobin molecule. These calculations have enabled us to identify the nearest-neighbour residues to each of the residues in the five antigenic sites, and which thus describe the immediate molecular environment of the sites. The influences of chemical changes or replacements in these environmental residues on the binding capacity of an antigenic site, when considered together with replacements directly in the antigenic sites, are expected to account for the major effects and will be extremely useful in explaining the cross-reactions of myoglobins from various species. However, it is stressed that the analysis has limitations due to the qualitative estimates of the effects, the influences of substitutions of once-removed or even at more distant locations (especially when they are cumulative) and finally the influences of any conformational re-adjustments when these occur as a result of the replacement(s).

scholarly journals The antibody response to myoglobin is independent of the immunized species. Analysis in terms of replacements in the antigenic sites and in environmental residues of the cross-reactions of fifteen myoglobins with sperm-whale myoglobin antisera raised in different species

1980 ◽  
Vol 191 (3) ◽  
pp. 681-697 ◽  
Author(s):  
S S Twining ◽  
H Lehmann ◽  
M Z Atassi
Keyword(s):  
Amino Acid ◽  
Antibody Response ◽  
Three Dimensional ◽  
Sperm Whale ◽  
Cross Reactivity ◽  
Antigenic Structure ◽  
Amino Acid Substitutions ◽  
Antigenic Sites ◽  
The Cross ◽  
Sperm Whale Myoglobin

The recent determination of the entire antigenic structure of sperm-whale myoglobin with rabbit and goat antisera has permitted the examination of whether the antigenic structure recognized by antibodies depends on the species in which the antisera are raised. Also, by knowledge of the antigenic structure, the molecular factors that determine and influence antigenicity can be better understood in terms of the effects of amino acid substitutions occurring in the antigenic sites and in the environmental residues of the sites. In the present work, the myoglobins from finback whale, killer whale, horse, chimpanzee, sheep, goat, bovine, echidna, viscacha, rabbit, dog, cape fox, mouse and chicken were examined for their ability to cross-react with antisera to sperm-whale myoglobin. By immunoadsorbent titration studies with radioiodinated antibodies, each of these myoglobins was able to bind antibodies to sperm-whale myoglobin raised in goat, rabbit, chicken, cat, pig and outbred mouse. It was found that the extent of cross-reaction of a given myoglobin was not dependent on the species in which the antisera were raised. This indicated that the antibody response to sperm-whale myoglobin (i.e. its antigenic structure) is independent of the species in which the antisera are raised and is not directed to regions of sequence differences between the injected myoglobin and the myoglobin of the immunized host. Indeed, in each antiserum from a given species examined, that antiserum reacted with the myoglobin of that species. The extent of this auto-reactivity for a given myoglobin was comparable with the general extent of cross-reactivity shown by that myoglobin with antisera raised in other species. The cross-reactivities and auto-reactivities (both of which are of similar extents for a given myoglobin) can be reasonably rationalized in terms of the effects of amino acid substitutions within the antigenic sites and within the residues close to these sites. These findings confirm that the antigenicity of the sites is inherent in their three-dimensional locations.

The structure of haemoglobin. IX. A three-dimensional Fourier synthesis at 5.5 Å resolution: description of the structure

1962 ◽  
Vol 265 (1321) ◽  
pp. 161-187 ◽  
Keyword(s):  
Tertiary Structure ◽  
Three Dimensional ◽  
Sperm Whale ◽  
Anomalous Scattering ◽  
Fourier Synthesis ◽  
Human Haemoglobin ◽  
Contour Maps ◽  
To Come ◽  
Polypeptide Chains ◽  
Sperm Whale Myoglobin

The electron density distribution in the unit cell is calculated at intervals of approximately 2Å and plotted in a series of sections parallel to (010). The contour maps show that haemoglobin consists of four subunits in a tetrahedral array. The subunits are identical in pairs in accordance with the twofold symmetry of the molecule. The two pairs are very similar in structure, and the members of each pair closely resemble the molecule of sperm-whale myoglobin. The four haem groups lie in separate pockets at the surface of the molecule. The positions of the iron atoms are confirmed by comparison of observed and calculated anomalous scattering effects, which also serve to determine the absolute configuration of the molecule. The four subunits found by X-ray analysis correspond to the four polypeptide chains into which haemoglobin can be divided by chemical methods. In horse haemoglobin the amino acid sequence within these chains is still partly unknown, but in human haemoglobin it has already been determined. Comparison of this sequence with the tertiary structure of the chains as now revealed in horse haemoglobin and with the atomic model of sperm-whale myoglobin recently obtained by Kendrew and his collaborators shows many interesting relations. Prolines appear to come where the chains turn corners or where their configuration is known to be non-helical. On the other hand, the chains also have corners which contain no proline. Certain residues appear to be structurally vital, because they appear in identical positions in myoglobin and in the two chains of haemoglobin, while in other parts of the molecule a wide variety of different side-chains appears to be allowed.

scholarly journals Antigenic structure of human haemoglobin. Localization of the antigenic sites of the β-chain in three host species by synthetic overlapping peptides representing the entire chain

1986 ◽  
Vol 234 (2) ◽  
pp. 441-447 ◽  
Author(s):  
N Yoshioka ◽  
M Z Atassi
Keyword(s):  
Host Species ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Antigenic Structure ◽  
Synthetic Approach ◽  
Immune Recognition ◽  
Beta Chain ◽  
Human Haemoglobin ◽  
Antigenic Sites ◽  
Full Profile

A comprehensive synthetic approach is applied here to localize the continuous antigenic sites of the beta-chain of haemoglobin. The approach was based on the synthesis and purification of the following consecutive 15-residue peptides (each overlapping by five residues at both ends with the peptides preceding it and following it in the sequence): 1-15, 11-25 etc. Quantitative radiometric titrations of protein and peptide adsorbents were performed with 125I-labelled anti-haemoglobin antibodies from three different host species. The specificity of antibody binding to peptide adsorbents was confirmed by inhibition studies and by the binding specificity of antibodies isolated from peptide adsorbents. These studies established the full profile of antigenic beta-chain regions, which was found to be independent of the host species. Five major antigenic sites were localized, and their three-dimensional and structural characteristics are discussed in relation to the immune recognition of haemoglobin and other proteins.

scholarly journals Structurally inherent antigenic sites. Localization of the antigenic sites of the α-chain of human haemoglobin in three host species by a comprehensive synthetic approach

1982 ◽  
Vol 203 (1) ◽  
pp. 201-208 ◽  
Author(s):  
A L Kazim ◽  
M Z Atassi
Keyword(s):  
Primary Structure ◽  
Host Species ◽  
Three Dimensional ◽  
Antigenic Structure ◽  
Synthetic Approach ◽  
Human Haemoglobin ◽  
Alpha Chain ◽  
Antigenic Sites ◽  
Full Profile ◽  
Related Proteins

The antigenic structure of the alpha-chain of human haemoglobin was studied by a synthetic approach consisting of the synthesis of a series of consecutive overlapping peptides that together systematically represent the entire primary structure of the protein. This approach enabled the identification of a full profile of immunochemically active alpha-chain peptides and the localization of its major ‘continuous’ antigenic sites. Antibodies to haemoglobin raised in each of three different species (goat, rabbit and mouse) recognize similar sites on the alpha-chain. Further, the molecular locations of these sites coincide with alpha-chain regions extrapolated from antigenic sites of the conformationally similar myoglobin molecule. These findings support our earlier proposed concept of ‘structurally inherent antigenic sites’, namely that antigenicity is conferred on certain surface regions of proteins by virtue of their three-dimensional locations. Thus the antigenic sites of conformationally related proteins are likely to have similar molecular locations.

scholarly journals A novel and comprehensive synthetic approach for the elucidation of protein antigenic structures. Determination of the full antigenic profile of the α-chain of human haemoglobin

1980 ◽  
Vol 191 (1) ◽  
pp. 261-264 ◽  
Author(s):  
A L Kazim ◽  
M Z Atassi
Keyword(s):  
Primary Structure ◽  
Synthetic Approach ◽  
Human Haemoglobin ◽  
Alpha Chain ◽  
Antigenic Sites ◽  
Full Profile ◽  
Α Chain ◽  
First Time ◽  
Antigenic Profile

A comprehensive synthetic approach for the determination of continuous antigenic sites of proteins is presented. This approach consists of the synthesis of a series of consecutive overlapping peptides that, together, systematically represent the entire primary structure of the protein under study. Its application to the alpha-chain of human haemoglobin afforded, for the first time, a full profile of immunochemically active alpha-chain peptides and enabled the localization of all the major continuous antigenic sites of this haemoglobin subunit.

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