Evidence and sources

Measurements

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Big picture numbers

Structures

• 2HHB
  Deoxy T state, full tetramer

  The reference T state and the hero of the scene. The whole alpha2beta2 tetramer sits in the asymmetric unit, so no assembly step is needed. Entry 4HHB carries the same title, resolution, atom count and citation. X-ray diffraction, 1.74 Å.
• 2DN2
  Deoxy T state at 1.25 A

  Highest-resolution T state, and the full tetramer is in the asymmetric unit. Best choice when the engine needs one T model and one R model from the same study. X-ray diffraction, 1.25 Å.
• 2DN3
  Carbonmonoxy R state at 1.25 A

  The R state partner for 2HHB and 2DN2. Load biological assembly 1, not the asymmetric unit, or only half the molecule appears. X-ray diffraction, 1.25 Å.
• 2DN1
  Oxy R state at 1.25 A

  The R state with oxygen rather than carbon monoxide. Use it when the caption says oxygen. X-ray diffraction, 1.25 Å.
• 1HHO
  Oxy R state, 1983 structure

  The classic oxy structure that defined the R state. Its measured rotation against 2HHB is 13.0 degrees, slightly less than the 1.25 A entries. X-ray diffraction, 2.1 Å.
• 1GZX
  T state with oxygen at all four hemes

  Separates the two halves of the mechanism. Ligand binding and the quaternary switch are different events, and this entry shows one without the other. X-ray diffraction, 2.1 Å.
• 1BBB
  A third quaternary structure, R2

  A liganded quaternary state that is neither classic T nor classic R, and a full tetramer in the asymmetric unit. RCSB records no DOI for its primary citation. X-ray diffraction, 1.7 Å.
• 1B86
  Tetramer with 2,3-BPG in the central cavity

  Shows where 2,3-BPG binds, which is the physical basis for treating pH and BPG as changes in the allosteric constant L. X-ray diffraction, 2.5 Å.
• 4MQJ
  Fetal hemoglobin, HbF

  The gamma-for-beta swap. RCSB lists the primary citation as unpublished, so no DOI is available. X-ray diffraction, 1.8 Å.
• 1FDH
  Fetal deoxyhaemoglobin, 1977 structure

  The deoxy fetal tetramer, for a T-state comparison with adult 2HHB. RCSB records no DOI for its primary citation. X-ray diffraction, 2.5 Å.
• 2HBS
  Sickle hemoglobin, deoxy

  The disease mutation. Two tetramers in one asymmetric unit also hint at the packing that leads to fibres. X-ray diffraction, 2.05 Å.
• 1HBB
  Hb Rothschild, beta Trp37 to Arg

  A mutation placed exactly at the switch interface, which makes it the sharpest test of the allosteric contact. RCSB records no DOI for its primary citation. X-ray diffraction, 1.9 Å.
• 1A6M
  Oxy myoglobin at 1.0 A

  The evolutionary control. One globin with one heme and no cooperativity, at the highest resolution in this set. X-ray diffraction, 1 Å.

References

1. 1Fermi et al., J Mol Biol 1984. The crystal structure of human deoxyhaemoglobin at 1.74 A resolution
2. 2Park et al., J Mol Biol 2006. 1.25 A resolution crystal structures of human haemoglobin in the oxy, deoxy and carbonmonoxy forms
3. 3Shaanan, J Mol Biol 1983. Structure of human oxyhaemoglobin at 2.1 A resolution
4. 4Paoli et al., J Mol Biol 1996. Crystal structure of T state haemoglobin with oxygen bound at all four haems
5. 5Richard et al., J Mol Biol 1993. Human deoxyhaemoglobin-2,3-diphosphoglycerate complex low-salt structure at 2.5 A resolution
6. 6Silva et al., J Biol Chem 1992. A third quaternary structure of human hemoglobin A at 1.7-A resolution
7. 7Kavanaugh et al., Biochemistry 1992. High-resolution X-ray study of deoxyhemoglobin Rothschild 37 beta Trp to Arg: a mutation that creates an intersubunit chloride-binding site
8. 8Harrington et al., J Mol Biol 1997. The high resolution crystal structure of deoxyhemoglobin S
9. 9Vojtechovsky et al., Biophys J 1999. Crystal structures of myoglobin-ligand complexes at near-atomic resolution
10. 10Monod et al., J Mol Biol 1965. On the nature of allosteric transitions: a plausible model
11. 11Perutz, Nature 1970. Stereochemistry of cooperative effects in haemoglobin: haem-haem interaction and the problem of allostery
12. 12Baldwin and Chothia, J Mol Biol 1979. Haemoglobin: the structural changes related to ligand binding and its allosteric mechanism
13. 13Yuan et al., Chem Rev 2015. New look at hemoglobin allostery
14. 14Yonetani and Tsuneshige, C R Biol 2003. The global allostery model of hemoglobin: an allosteric mechanism involving homotropic and heterotropic interactions
15. 15Benesch and Benesch, Biochem Biophys Res Commun 1967. The effect of organic phosphates from the human erythrocyte on the allosteric properties of hemoglobin
16. 16van der Plas et al., Transfusion 1988. Purification and physical characteristics of a hemoglobin solution modified by coupling to 2-nor-2-formylpyridoxal 5'-phosphate
17. 17Cambier et al., Vet J 2005. Blood-oxygen binding in healthy Standardbred horses
18. 18Clerbaux et al., Comp Biochem Physiol A 1993. Comparative study of the oxyhaemoglobin dissociation curve of four mammals: man, dog, horse and cattle
19. 19Tsai et al., Biophys Chem 2003. Site mutations disrupt inter-helical H-bonds involved in kinetic steps in the hemoglobin R to T transition without altering the free energies of oxygenation
20. 20Fronticelli et al., Eur J Biochem 1990. Bovine hemoglobin pseudo-crosslinked with mono(3,5-dibromosalicyl)-fumarate
21. 21Weber et al., J Comp Physiol B 1987. Analysis of teleost hemoglobin by Adair and Monod-Wyman-Changeux models
22. 22Hardison, Cold Spring Harb Perspect Med 2012. Evolution of hemoglobin and its genes
23. 23Sankaran and Orkin, Cold Spring Harb Perspect Med 2013. The switch from fetal to adult hemoglobin
24. 24Takahashi et al., Nat Commun 2024. The unique allosteric property of crocodilian haemoglobin elucidated by cryo-EM
25. 25Shibayama, Protein Sci 2025. Effects of allosteric effectors on oxygen binding to crystals of hemoglobin in the R-quaternary structure