Analysis of a complex antigenic site on horse cytochrome c.
Abstract: Of the antigenic determinants so far identified for cytochrome c, only one involves more than a single amino acid substitution between the immunogen and host proteins. Both a threonine at position 89 and a glutamic acid at position 92 control one of the three antigenic sites identified in horse cytochrome c, as expressed in rabbits. Three antibody subpopulations, all directed against this region of the molecule, were isolated from the serum of a single rabbit by adsorption on a series of insolubilized cytochromes c. Antibody fluorescence quenching titrations with a variety of cytochromes c were used to confirm the identification of the antigenic determinant and to examine the subtle differences in the specificities of the three subpopulations. The determinant in the region of Residues 89-92 is affected by amino acid substitutions at positions 88 and 96. Since all these residues are in an alpha-helix the farthest distance between them is only 12 A and therefore, the Residues 88-96 can all be accommodated in the antibody binding site. The ability to identify and describe the antigenic determinant, as well as separate subpopulations directed against this site, demonstrates the resolution possible using a series of homologous protein antigens.
Publication Date: 1978-01-01 PubMed ID: 82379DOI: 10.1007/978-1-4615-8858-0_6Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The study explores the specific regions of the horse cytochrome c molecule that elicit an immune response in rabbits. It is discovered that three separate antibody subpopulations target the region spanning residues 88-96, with variants in positions 88 and 96 influencing the antigenic site.
Overview and Objectives of the Research
- The research aims to identify and analyze an intricate antigenic site on the horse cytochrome c molecule. This is significant as cytochrome c is a crucial protein involved in cellular respiration and the ancestral sequence was one of the first to be determined.
- One particular objective was to describe the determinant affected by amino acid substitutions at positions 88 and 96 in the alpha-helix structure, spanning the Residues 89-96.
- The study also intends to investigate the specificities of three separate antibody subpopulations targeting this region.
Methodology
- The researchers used antibody fluorescence quenching titrations with various cytochromes c to confirm the identification of the antigenic determinant. This method involves tracking the decrease in fluorescence upon binding of an antibody, giving measure of the specificity and strength of antigen-antibody interactions.
- The antibody subpopulations were isolated from the serum of a single rabbit by absorption on a series of insolubilized cytochromes c. This points to the ability to separate different antibody responses towards the antigenic site.
Findings
- The antigenic determinant for the horse cytochrome c was found in the region of residues 89-92, which is under the influence of amino acid substitutions at locations 88 and 96.
- Importantly, the three identified antibody subpopulations target this region, showcasing the high specificity of antigen-antibody interactions.
- Because of the alpha-helix structure across these residues and a maximum distance of only 12 Angstroms between them, all these residues can fit within the antibody binding site.
Implications
- The ability to identify and distinguish different subpopulations of antibodies targeting this specific site highlights the level of detail achievable with homologous protein antigens.
- This work contributes to a deeper understanding of antigen-antibody interactions, specifically when it comes to complex antigenic sites involving multiple varied residues.
Cite This Article
APA
Jemmerson R, Margoliash E.
(1978).
Analysis of a complex antigenic site on horse cytochrome c.
Adv Exp Med Biol, 98, 119-129.
https://doi.org/10.1007/978-1-4615-8858-0_6 Publication
Researcher Affiliations
MeSH Terms
- Amino Acid Sequence
- Amino Acids / immunology
- Animals
- Cross Reactions
- Cytochrome c Group / immunology
- Epitopes
- Horses / immunology
- Species Specificity
Citations
This article has been cited 1 times.- Solinger AM, Ultee ME, Margoliash E, Schwartz RH. T-lymphocyte response to cytochrome c. I. Demonstration of a T-cell heteroclitic proliferative response and identification of a topographic antigenic determinant on pigeon cytochrome c whose immune recognition requires two complementing major histocompatibility complex-linked immune response genes.. J Exp Med 1979 Oct 1;150(4):830-48.
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