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Home / Equine Research Bank / Proc Natl Acad Sci U S A / Measurement of ligand-induced conformational changes in hemo...
Proceedings of the National Academy of Sciences of the United States of America1969; 63(1); 205-212; doi: 10.1073/pnas.63.1.205

Measurement of ligand-induced conformational changes in hemoglobin by circular dichroism.

Abstract: The UV circular-dichroism spectra of human and horse hemoglobins have been determined at various degrees of partial saturation with oxygen. Spectra of the two native hemoglobins were compared with spectra of the corresponding proteins modified with a reagent known to eliminate the conformational rearrangement normally associated with cooperativity. Such comparison indicates that one region, around 260 mmu, is sensitive chiefly to the state of the hemes; changes in another region, around 285 mmu, may be correlated with the conformational transformation linked to cooperative interactions. All circular-dichroism changes are strictly linear with fractional saturation with oxygen. Possible implications of these results to recently proposed mechanisms for cooperativity in proteins are discussed.
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Publication Date: 1969-05-01 PubMed ID: 5257964PubMed Central: PMC534023DOI: 10.1073/pnas.63.1.205Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper explores how different levels of oxygen saturation influence the structural changes in human and horse hemoglobins, using a methodology known as UV circular-dichroism spectra.

Objective of the Study

  • The primary purpose of this study was to examine the conformational changes in hemoglobin resulting from ligand binding by utilizing UV circular-dichroism spectra. It aimed to observe how the changes occur with various degrees of partial saturation with oxygen in both human and horse hemoglobins.

Methodology

  • The helix-coil transition concept was applied to examine the UV circular-dichroism spectra of human and horse hemoglobin with varied oxygen saturation levels.
  • The study also compared spectra of native hemoglobin with those of corresponding proteins modified with a specific reagent designed to eliminate the conformational rearrangement typically associated with cooperativity. This would reveal the impact of oxygen saturation on the conformational changes in hemoglobin.

Findings

  • The study showed that one region of the protein, located around 260 mmu, is mainly sensitive to the hemes state. This indicates that the oxygen binding leads to a structural impact on the hemes.
  • Another protein region, around 285 mmu, experiences changes that could be linked with the conformational transformation related to cooperative interactions. This suggests that oxygen binding not only cause structural shifts but also influence the cooperative interactions that play a crucial role in protein function.
  • All changes in circular-dichroism were strictly linear with the varying degrees of saturation by oxygen. This means that the response of the protein to oxygen binding remains consistent across all levels of saturation.

Concluding Remarks and Implications

  • The findings of this research can potentially contribute to a better understanding of the mechanisms of cooperativity in proteins, especially those related to oxygen binding.
  • The results challenge some of the mechanisms proposed previously for cooperativity in proteins, paving the way for further research and discussion on this topic.

Cite This Article

APA
Simon SR, Cantor CR. (1969). Measurement of ligand-induced conformational changes in hemoglobin by circular dichroism. Proc Natl Acad Sci U S A, 63(1), 205-212. https://doi.org/10.1073/pnas.63.1.205

Publication

Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
NlmUniqueID: 7505876
Country: United States
Language: English
Volume: 63
Issue: 1
Pages: 205-212

Researcher Affiliations

Simon, S R
    Cantor, C R

      MeSH Terms

      • Animals
      • Hemoglobins / analysis
      • Horses
      • Humans
      • Methods
      • Oxygen
      • Spectrum Analysis
      • Ultraviolet Rays

      References

      This article includes 16 references
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      Citations

      This article has been cited 2 times.
      1. Chen Q, Lalezari I, Nagel RL, Hirsch RE. Liganded hemoglobin structural perturbations by the allosteric effector L35.. Biophys J 2005 Mar;88(3):2057-67.
        doi: 10.1529/biophysj.104.046136pubmed: 15626716google scholar: lookup
      2. Sawicki CA, Gibson QH. The relation between carbon monoxide binding and the conformational change of hemoglobin.. Biophys J 1978 Oct;24(1):21-33.
        doi: 10.1016/S0006-3495(78)85328-4pubmed: 30492google scholar: lookup
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