Hemoglobin, alpha 2

Hemoglobin, alpha 2 also known as HBA2 is a gene that in humans codes for the alpha globin chain of hemoglobin.^[1][2]

Function

The human alpha globin gene cluster is located on chromosome 16 and spans about 30 kb, including seven alpha like globin genes and pseudogenes: 5'- HBZ - HBZP1 - HBM - HBAP1 - HBA2 - HBA1 - HBQ1 -3'. The HBA2 (α₂) and HBA1 (α₁) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions.

Protein

Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin.

Clinical significance

Alpha-thalassemias most commonly result from deletions of any of the four alpha genes, although some alpha thalassemias have been reported that are due to mutations other than deletion. Deletion of 1 or 2 alleles is clinically silent. Deletion of 3 alleles causes HbH disease, resulting in anemia and hepatosplenomegaly. Deletion of all 4 alleles is lethal because it renders the body unable to make fetal hemoglobin (HbF), adult hemoglobin (HbA) or adult variant hemoglobin (HbA2), and results in hydrops fetalis.^[3]

References

Further reading

External links

• GeneReviews/NCBI/NIH/UW entry on Alpha-Thalassemia
• OMIM etries on Alpha-Thalassemia

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

PDB gallery 1hbb: HIGH-RESOLUTION X-RAY STUDY OF DEOXYHEMOGLOBIN ROTHSCHILD 37BETA TRP-> ARG: A MUTATION THAT CREATES AN INTERSUBUNIT CHLORIDE-BINDING SITE  1ye1: T-To-T(High) quaternary transitions in human hemoglobin: betaY35A oxy (2MM IHP, 20% PEG) (1 test set)  1xye: T-to-THigh Transitions in Human Hemoglobin: alpha Y42A deoxy low salt  1y4g: T-To-T(High) quaternary transitions in human hemoglobin: betaW37G deoxy low-salt (10 test sets)  1y7d: T-To-T(High) quaternary transitions in human hemoglobin: betaP100G deoxy low-salt (1 test set)  1buw: CRYSTAL STRUCTURE OF S-NITROSO-NITROSYL HUMAN HEMOGLOBIN A  1yh9: T-to-T(High) quaternary transitions in human hemoglobin: HbA OXY (2MM IHP, 20% PEG) (10 test sets)  1shr: Crystal structure of ferrocyanide bound human hemoglobin A2 at 1.88A resolution  1yeq: T-To-T(High) quaternary transitions in human hemoglobin: betaW37Y OXY (10 test sets)  1hco: THE STRUCTURE OF HUMAN CARBONMONOXY HAEMOGLOBIN AT 2.7 ANGSTROMS RESOLUTION  1coh: STRUCTURE OF HAEMOGLOBIN IN THE DEOXY QUATERNARY STATE WITH LIGAND BOUND AT THE ALPHA HAEMS  1ljw: Crystal Structure of Human Carbonmonoxy Hemoglobin at 2.16 A: A Snapshot of the Allosteric Transition  1ye0: T-To-T(High) quaternary transitions in human hemoglobin: betaV33A oxy (2MM IHP, 20% PEG) (1 test set)  1j7y: Crystal structure of partially ligated mutant of HbA  1hgc: HIGH RESOLUTION CRYSTAL STRUCTURES AND COMPARISONS OF T STATE DEOXYHAEMOGLOBIN AND TWO LIGANDED T-STATE HAEMOGLOBINS: T(ALPHA-OXY)HAEMOGLOBIN AND T(MET)HAEMOGLOBIN  1hbs: REFINED CRYSTAL STRUCTURE OF DEOXYHEMOGLOBIN S. I. RESTRAINED LEAST-SQUARES REFINEMENT AT 3.0-ANGSTROMS RESOLUTION  2dn3: 1.25A resolution crystal structure of human hemoglobin in the carbonmonoxy form  1qsi: MAGNESIUM(II)-AND ZINC(II)-PROTOPORPHYRIN IX'S STABILIZE THE LOWEST OXYGEN AFFINITY STATE OF HUMAN HEMOGLOBIN EVEN MORE STRONGLY THAN DEOXYHEME  1qsh: MAGNESIUM(II)-AND ZINC(II)-PROTOPORPHYRIN IX'S STABILIZE THE LOWEST OXYGEN AFFINITY STATE OF HUMAN HEMOGLOBIN EVEN MORE STRONGLY THAN DEOXYHEME  3hhb: THE CRYSTAL STRUCTURE OF HUMAN DEOXYHAEMOGLOBIN AT 1.74 ANGSTROMS RESOLUTION  1k0y: X-ray Crystallographic Analyses of Symmetrical Allosteric Effectors of Hemoglobin. Compounds Designed to Link Primary and Secondary Binding Sites  1gbv: (ALPHA-OXY, BETA-(C112G)DEOXY) T-STATE HUMAN HEMOGLOBIN  1ygf: T-to-T(high) quaternary transitions in human hemoglobin: betaH97A oxy (2MM IHP, 20% PEG) (1 test set)  1dxt: HIGH-RESOLUTION X-RAY STUDY OF DEOXY RECOMBINANT HUMAN HEMOGLOBINS SYNTHESIZED FROM BETA-GLOBINS HAVING MUTATED AMINO TERMINI  2hbs: THE HIGH RESOLUTION CRYSTAL STRUCTURE OF DEOXYHEMOGLOBIN S  1y22: T-To-T(High) quaternary transitions in human hemoglobin: betaV33A deoxy low-salt (1 test set)  1lfv: OXY HEMOGLOBIN (88% RELATIVE HUMIDITY)  1hac: CROSSLINKED HAEMOGLOBIN  1y0t: T-to-T(High) Quaternary Transitions in Human Hemoglobin: betaV1M deoxy low-salt (1 test set)  1y8w: T-To-T(High) quaternary transitions in human hemoglobin: alphaR92A oxy (2mM IHP, 20% PEG) (10 test sets)  1nih: Structure of deoxy-quaternary haemoglobin with liganded beta subunits  1rqa: Crystallographic Analysis of the Interaction of Nitric Oxide with Quaternary-T Human Hemoglobin. Beta W73E hemoglobin exposed to NO under anaerobic conditions  1lfq: OXY HEMOGLOBIN (93% RELATIVE HUMIDITY)  1xz2: wild-type hemoglobin deoxy no-salt  1m9p: Crystalline Human Carbonmonoxy Hemoglobin C Exhibits The R2 Quaternary State at Neutral pH In The Presence of Polyethylene Glycol: The 2.1 Angstrom Resolution Crystal Structure  1thb: REFINEMENT OF A PARTIALLY OXYGENATED T STATE HAEMOGLOBIN AT 1.5 ANGSTROMS RESOLUTION  1yvq: The low salt (PEG) crystal structure of CO Hemoglobin E (betaE26K) approaching physiological pH (pH 7.5)  2hhb: THE CRYSTAL STRUCTURE OF HUMAN DEOXYHAEMOGLOBIN AT 1.74 ANGSTROMS RESOLUTION  1xy0: T-to-THigh Transitions in Human Hemoglobin: alphaK40G deoxy low-salt  6hbw: Crystal structure of deoxy-human hemoglobin beta6 glu->trp  1bab: HEMOGLOBIN THIONVILLE: AN ALPHA-CHAIN VARIANT WITH A SUBSTITUTION OF A GLUTAMATE FOR VALINE AT NA-1 AND HAVING AN ACETYLATED METHIONINE NH2 TERMINUS  2hhd: OXYGEN AFFINITY MODULATION BY THE N-TERMINI OF THE BETA-CHAINS IN HUMAN AND BOVINE HEMOGLOBIN  2dn1: 1.25A resolution crystal structure of human hemoglobin in the oxy form  1y09: T-to-T(High) Quaternary Transitions in Human Hemoglobin: alphaN97A deoxy low-salt  1lfl: DEOXY HEMOGLOBIN (90% RELATIVE HUMIDITY)  1y0c: T-to-THigh Quaternary Transitions in Human Hemoglobin: alphaY140F deoxy low-salt  1sdl: CROSS-LINKED, CARBONMONOXY HEMOGLOBIN A  1o1o: Deoxy hemoglobin (A,C:V1M,V62L; B,D:V1M,V67L)  1yih: T-to-T(High) quaternary transitions in human hemoglobin: betaP100A oxy (2.2MM IHP, 20% PEG) (1 test set)  1qxd: Structural Basis for the Potent Antisickling Effect of a Novel Class of 5-Membered Heterocyclic Aldehydic Compounds  1y4q: T-To-T(High) quaternary transitions in human hemoglobin: betaF42A deoxy low-salt (1 test set)  1y85: T-To-T(High) quaternary transitions in human hemoglobin: desHIS146beta deoxy low-salt  1fn3: CRYSTAL STRUCTURE OF NICKEL RECONSTITUTED HEMOGLOBIN-A CASE FOR PERMANENT, T-STATE HEMOGLOBIN  1a9w: HUMAN EMBRYONIC GOWER II CARBONMONOXY HEMOGLOBIN  1jy7: THE STRUCTURE OF HUMAN METHEMOGLOBIN. THE VARIATION OF A THEME  1a3n: DEOXY HUMAN HEMOGLOBIN  1yg5: T-To-T(High) quaternary transitions in human hemoglobin: betaW37H OXY (2MM IHP, 20% PEG) (10 test sets)  1dxv: HIGH-RESOLUTION X-RAY STUDY OF DEOXY RECOMBINANT HUMAN HEMOGLOBINS SYNTHESIZED FROM BETA-GLOBINS HAVING MUTATED AMINO TERMINI  1hga: HIGH RESOLUTION CRYSTAL STRUCTURES AND COMPARISONS OF T STATE DEOXYHAEMOGLOBIN AND TWO LIGANDED T-STATE HAEMOGLOBINS: T(ALPHA-OXY)HAEMOGLOBIN AND T(MET)HAEMOGLOBIN  1b86: HUMAN DEOXYHAEMOGLOBIN-2,3-DIPHOSPHOGLYCERATE COMPLEX  1xz5: T-to-THigh Quaternary Transitions in Human Hemoglobin: alphaL91A deoxy low-salt  1y46: T-To-T(High) quaternary transitions in human hemoglobin: betaW37Y deoxy low-salt (10 test sets)  1yen: T-To-T(High) quaternary transitions in human hemoglobin: betaP36A oxy (2MM IHP, 20% PEG) (10 test sets)  1yzi: A novel quaternary structure of human carbonmonoxy hemoglobin  2hhe: OXYGEN AFFINITY MODULATION BY THE N-TERMINI OF THE BETA CHAINS IN HUMAN AND BOVINE HEMOGLOBIN  1a01: HEMOGLOBIN (VAL BETA1 MET, TRP BETA37 ALA) MUTANT  2hbf: HIGH RESOLUTION X-RAY STRUCTURES OF MYOGLOBIN-AND HEMOGLOBIN-ALKYL ISOCYANIDE COMPLEXES  2d5z: Crystal structure of T-state human hemoglobin complexed with three L35 molecules  1c7d: DEOXY RHB1.2 (RECOMBINANT HEMOGLOBIN)  3d17: A triply ligated crystal structure of relaxed state human hemoglobin  2hbc: HIGH RESOLUTION X-RAY STRUCTURES OF MYOGLOBIN-AND HEMOGLOBIN-ALKYL ISOCYANIDE COMPLEXES  1o1i: Cyanomet hemoglobin (A-GLY-C:V1M,L29F,H58Q; B,D:V1M,L106W)  1gli: DEOXYHEMOGLOBIN T38W (ALPHA CHAINS), V1G (ALPHA AND BETA CHAINS)  1qi8: DEOXYGENATED STRUCTURE OF A DISTAL POCKET HEMOGLOBIN MUTANT  1a0z: HEMOGLOBIN (VAL BETA1 MET) MUTANT  1cmy: THE MUTATION BETA99 ASP-TYR STABILIZES Y-A NEW, COMPOSITE QUATERNARY STATE OF HUMAN HEMOGLOBIN  1o1p: Deoxy hemoglobin (A-GLY-C:V1M; B,D:V1M,C93A,N108K)  1j7w: Crystal structure of deoxy HbbetaYQ, a site directed mutant of HbA  1aj9: R-STATE HUMAN CARBONMONOXYHEMOGLOBIN ALPHA-A53S  1dke: NI BETA HEME HUMAN HEMOGLOBIN  1bz1: HEMOGLOBIN (ALPHA + MET) VARIANT  1o1m: Deoxy hemoglobin (A-GLYGLYGLY-C:V1M,L29F,H58Q B,D:V1M,V67W)  1y4f: T-To-T(High) quaternary transitions in human hemoglobin: betaW37A deoxy low-salt (10 test sets)  1y2z: T-To-T(High) quaternary transitions in human hemoglobin: betaV34G deoxy low-salt (1 test set)  1rq3: Crystallographic Analysis of the Interaction of Nitric Oxide with Quaternary-T Human Deoxyhemoglobin, Deoxyhemoglobin  1j3z: Direct observation of photolysis-induced tertiary structural changes in human haemoglobin; Crystal structure of alpha(Fe-CO)-beta(Ni) hemoglobin (laser unphotolysed)  1lft: OXY HEMOGLOBIN (90% RELATIVE HUMIDITY)  1lfz: OXY HEMOGLOBIN (25% METHANOL)  1bij: CROSSLINKED, DEOXY HUMAN HEMOGLOBIN A  1cls: CROSS-LINKED HUMAN HEMOGLOBIN DEOXY  2dn2: 1.25A resolution crystal structure of human hemoglobin in the deoxy form  1vwt: T STATE HUMAN HEMOGLOBIN [ALPHA V96W], ALPHA AQUOMET, BETA DEOXY  1y7z: T-To-T(High) quaternary transitions in human hemoglobin: betaN108A deoxy low-salt (1 test set)  1nej: Crystalline Human Carbonmonoxy Hemoglobin S (Liganded Sickle Cell Hemoglobin) Exhibits The R2 Quaternary State At Neutral pH In The Presence Of Polyethylene Glycol: The 2.1 Angstrom Resolution Crystal Structure  1yev: T-To-T(High) quaternary transitions in human hemoglobin: betaW37E OXY (10 test sets)  1yhe: T-To-T(High) quaternary transitions in human hemoglobin: HbA OXY (5.0MM IHP, 20% PEG) (10 test sets)  1o1k: Deoxy hemoglobin (A,C:V1M; B,D:V1M,V67W)  1fdh: STRUCTURE OF HUMAN FOETAL DEOXYHAEMOGLOBIN  1a0u: HEMOGLOBIN (VAL BETA1 MET) MUTANT  1hab: CROSSLINKED HAEMOGLOBIN  1y0a: T-to-THigh Quaternary Transitions in Human Hemoglobin: alphaY140A deoxy low-salt  1rps: Crystallographic Analysis of the Interaction of Nitric Oxide with Quaternary-T Human Hemoglobin. Hemoglobin exposed to NO under anerobic conditions  1o1n: Deoxy hemoglobin (A-GLYGLYGLY-C:V1M,L29W; B,D:V1M)  1yie: T-to-thigh quaternary transitions in human hemoglobin: betaW37A oxy (2.2MM IHP, 13% PEG) (1 test set)  2hbe: HIGH RESOLUTION X-RAY STRUCTURES OF MYOGLOBIN-AND HEMOGLOBIN-ALKYL ISOCYANIDE COMPLEXES  1y5k: T-To-T(High) quaternary transitions in human hemoglobin: betaD99A deoxy low-salt (10 test sets)  1hba: HIGH-RESOLUTION X-RAY STUDY OF DEOXYHEMOGLOBIN ROTHSCHILD 37BETA TRP-> ARG: A MUTATION THAT CREATES AN INTERSUBUNIT CHLORIDE-BINDING SITE  1nqp: Crystal structure of Human hemoglobin E at 1.73 A resolution  1a00: HEMOGLOBIN (VAL BETA1 MET, TRP BETA37 TYR) MUTANT  2dxm: Neutron Structure Analysis of Deoxy Human Hemoglobin  1y7c: T-To-T(High) quaternary transitions in human hemoglobin: betaP100A deoxy low-salt (1 test set)  1o1j: Deoxy hemoglobin (A-GLY-C:V1M,L29F,H58Q; B,D:V1M,L106W)  1uiw: Crystal Structures of Unliganded and Half-Liganded Human Hemoglobin Derivatives Cross-Linked between Lys 82beta1 and Lys 82beta2  2hco: THE STRUCTURE OF HUMAN CARBONMONOXY HAEMOGLOBIN AT 2.7 ANGSTROMS RESOLUTION  1y5f: T-To-T(High) quaternary transitions in human hemoglobin: betaL96A deoxy low-salt (1 test set)  1hgb: HIGH RESOLUTION CRYSTAL STRUCTURES AND COMPARISONS OF T STATE DEOXYHAEMOGLOBIN AND TWO LIGANDED T-STATE HAEMOGLOBINS: T(ALPHA-OXY)HAEMOGLOBIN AND T(MET)HAEMOGLOBIN  1xxt: The T-to-T High Transitions in Human Hemoglobin: wild-type deoxy Hb A (low salt, one test set)  2h35: Solution structure of Human normal adult hemoglobin  1r1x: Crystal structure of oxy-human hemoglobin Bassett at 2.15 angstrom  1y83: T-To-T(High) quaternary transitions in human hemoglobin: betaY145G deoxy low-salt (1 test set)  1xzv: T-to-THigh Quaternary Transitions in Human Hemoglobin: alphaP95A deoxy low-salt  1qxe: Structural Basis for the Potent Antisickling Effect of a Novel Class of 5-Membered Heterocyclic Aldehydic Compounds  1lfy: OXY HEMOGLOBIN (84% RELATIVE HUMIDITY)  1mko: A Fourth Quaternary Structure of Human Hemoglobin A at 2.18 A Resolution  1dxu: HIGH-RESOLUTION X-RAY STUDY OF DEOXY RECOMBINANT HUMAN HEMOGLOBINS SYNTHESIZED FROM BETA-GLOBINS HAVING MUTATED AMINO TERMINI  1g9v: HIGH RESOLUTION CRYSTAL STRUCTURE OF DEOXY HEMOGLOBIN COMPLEXED WITH A POTENT ALLOSTERIC EFFECTOR  1sdk: CROSS-LINKED, CARBONMONOXY HEMOGLOBIN A  1yff: STRUCTURE OF HUMAN CARBONMONOXYHEMOGLOBIN C (BETA E6K): TWO QUATERNARY STATES (R2 and R3) IN ONE CRYSTAL  1ye2: T-To-T(High) quaternary transitions in human hemoglobin: betaY35F oxy (2MM IHP, 20% PEG) (1 test set)  1y4p: T-To-T(high) quaternary transitions in human hemoglobin: betaW37E deoxy low-salt (10 test sets)  1y4b: T-To-T(High) quaternary transitions in human hemoglobin: betaW37H deoxy low-salt (10 test sets)  1y0w: T-to-THigh quaternary Transitions in Human Hemoglobin: betaV1M deoxy low-salt (10 test sets)  1j41: Direct observation of photolysis-induced tertiary structural changes in human haemoglobin; Crystal structure of alpha(Ni)-beta(Fe) hemoglobin (laser photolysed)  1kd2: Crystal Structure of Human Deoxyhemoglobin in Absence of Any Anions  1y35: T-To-T(High) quaternary transitions in human hemoglobin: betaY35F deoxy low-salt (1 test set)  1si4: Crystal structure of Human hemoglobin A2 (in R2 state) at 2.2 A resolution  1ygd: T-To-T(High) quaternary transitions in human hemoglobin: betaW37E alpha zinc beta oxy (10 TEST SETS)  1c7b: DEOXY RHB1.0 (RECOMBINANT HEMOGLOBIN)  1yhr: T-To-T(High) quaternary transitions in human hemoglobin: HbA OXY (10.0MM IHP, 20% PEG) (10 test sets)  1rq4: Crystallographic Analysis of the Interaction of Nitric Oxide with Quaternary-T Human Hemoglobin, HEMOGLOBIN EXPOSED TO NO UNDER AEROBIC CONDITIONS  1y5j: T-To-T(High) quaternary transitions in human hemoglobin: betaH97A deoxy low-salt (1 test set)  1y4v: T-To-T(High) quaternary transitions in human hemoglobin: betaC93A deoxy low-salt (1 test set)  1xz7: T-to-THigh Quaternary Transitions in Human Hemoglobin: alphaR92A deoxy low-salt  1y31: T-To-T(High) quaternary transitions in human hemoglobin: betaY35A deoxy low-salt (1 test set)  1bz0: HEMOGLOBIN A (HUMAN, DEOXY, HIGH SALT)  1y7g: T-To-T(high) quaternary transitions in human hemoglobin: betaN102A deoxy low-salt (1 test set)  1hho: STRUCTURE OF HUMAN OXYHAEMOGLOBIN AT 2.1 ANGSTROMS RESOLUTION  1r1y: Crystal structure of deoxy-human hemoglobin Bassett at 1.8 angstrom  1y0d: T-to-THigh Quaternary Transitions in Human Hemoglobin: desArg141alpha deoxy low-salt  1bbb: A THIRD QUATERNARY STRUCTURE OF HUMAN HEMOGLOBIN A AT 1.7-ANGSTROMS RESOLUTION  1xz4: Intersubunit Interactions Associated with Tyr42alpha Stabilize the Quaternary-T Tetramer but are not Major Quaternary Constraints in Deoxyhemoglobin: alphaY42A deoxyhemoglobin no-salt  1a3o: ARTIFICIAL MUTANT (ALPHA Y42H) OF DEOXY HEMOGLOBIN  1rvw: R STATE HUMAN HEMOGLOBIN [ALPHA V96W], CARBONMONOXY  1y01: Crystal structure of AHSP bound to Fe(II) alpha-hemoglobin  1y45: T-To-T(high) quaternary transitions in human hemoglobin: betaP36A deoxy low-salt (10 test sets)  4hhb: THE CRYSTAL STRUCTURE OF HUMAN DEOXYHAEMOGLOBIN AT 1.74 ANGSTROMS RESOLUTION  1bzz: HEMOGLOBIN (ALPHA V1M) MUTANT  2d60: Crystal structure of deoxy human hemoglobin complexed with two L35 molecules  1hdb: ANALYSIS OF THE CRYSTAL STRUCTURE, MOLECULAR MODELING AND INFRARED SPECTROSCOPY OF THE DISTAL BETA-HEME POCKET VALINE67(E11)-THREONINE MUTATION OF HEMOGLOBIN  1yvt: The high salt (phosphate) crystal structure of CO Hemoglobin E (Glu26Lys) at physiological pH (pH 7.35)  2yrs: Human hemoglobin D Los Angeles: crystal structure  1yeo: T-To-T(High) quaternary transitions in human hemoglobin: betaW37A OXY (10 test sets)  1j40: Direct observation of photolysis-induced tertiary structural changes in human haemoglobin; Crystal structure of alpha(Ni)-beta(Fe-CO) hemoglobin (laser unphotolysed)  1j7s: Crystal Structure of deoxy HbalphaYQ, a mutant of HbA  1j3y: Direct observation of photolysis-induced tertiary structural changes in human hemoglobin; Crystal structure of alpha(Fe)-beta(Ni) hemoglobin (laser photolysed)  1z8u: Crystal structure of oxidized alpha hemoglobin bound to AHSP  1ydz: T-To-T(High) quaternary transitions in human hemoglobin: alphaY140F oxy (2MM IHP, 20% PEG) (1 test set)  1k1k: Structure of Mutant Human Carbonmonoxyhemoglobin C (beta E6K) at 2.0 Angstrom Resolution in Phosphate Buffer.  1c7c: DEOXY RHB1.1 (RECOMBINANT HEMOGLOBIN)  2hbd: HIGH RESOLUTION X-RAY STRUCTURES OF MYOGLOBIN-AND HEMOGLOBIN-ALKYL ISOCYANIDE COMPLEXES  1gbu: DEOXY (BETA-(C93A,C112G)) HUMAN HEMOGLOBIN  1aby: CYANOMET RHB1.1 (RECOMBINANT HEMOGLOBIN)  1gzx: OXY T STATE HAEMOGLOBIN: OXYGEN BOUND AT ALL FOUR HAEMS  1xzu: T-to-THigh Quaternary Transitions in Human Hemoglobin: alphaD94G deoxy low-salt  1yeu: T-To-T(High) quaternary transitions in human hemoglobin: betaW37G OXY (10 test sets)  1o1l: Deoxy hemoglobin (A-GLY-C:V1M,L29W,H58Q; B,D:V1M)  1abw: DEOXY RHB1.1 (RECOMBINANT HEMOGLOBIN)  1ird: Crystal Structure of Human Carbonmonoxy-Haemoglobin at 1.25 A Resolution  1y4r: T-To-T(High) quaternary transitions in human hemoglobin: betaF45A deoxy low-salt (1 test set)