2hhe
From Proteopedia
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| - | [[Image:2hhe.gif|left|200px]]<br /> | + | [[Image:2hhe.gif|left|200px]]<br /><applet load="2hhe" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="2hhe" size=" | + | |
caption="2hhe, resolution 2.2Å" /> | caption="2hhe, resolution 2.2Å" /> | ||
'''OXYGEN AFFINITY MODULATION BY THE N-TERMINI OF THE BETA CHAINS IN HUMAN AND BOVINE HEMOGLOBIN'''<br /> | '''OXYGEN AFFINITY MODULATION BY THE N-TERMINI OF THE BETA CHAINS IN HUMAN AND BOVINE HEMOGLOBIN'''<br /> | ||
==Overview== | ==Overview== | ||
| - | A mutant human hemoglobin, beta (V1M+H2 delta), has been constructed. | + | A mutant human hemoglobin, beta (V1M+H2 delta), has been constructed. Analysis of the oxygen binding curves obtained at pH 8.3, where the Bohr effect is inoperative, indicates that this mutation results in an additional stabilization of the T-state conformation by 0.9 kcal/mol. The crystal structure of deoxy-beta (V1M+H2 delta) has been determined to 2.2-A resolution and compared with the deoxy structure of human hemoglobin at the same resolution. In human hemoglobin, a sulfate anion is anchored to the beta-chains by a complex network of H-bonds and electrostatic interactions with the amino terminus and Lys beta 82. In the mutant hemoglobin, the shortening of the amino-terminal region of the A helix by 1 residue results in the formation of an intrachain electrostatic interaction between the amino-terminal amino and Asp beta 79. This eliminates the sulfate binding site, and the sulfate is replaced by two water molecules. At variance with human hemoglobin, the alkaline Bohr effect for beta (V1M+H2 delta) is not sensitive to the presence of Cl-. This indicates that the sulfate binding site in human hemoglobin also serves as a Cl- binding site, and that the amino-terminal Val beta 1 is essential for oxygen-linked Cl- binding to hemoglobin as well as the Cl(-)-dependent Bohr effect. Analysis of the oxygen binding curves indicates that the oxygen-linked Cl- ions are released upon binding of the first oxygen molecule. |
==Disease== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 2HHE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with HEM as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 2HHE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HHE OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Fronticelli, C.]] | [[Category: Fronticelli, C.]] | ||
| - | [[Category: Gilliland, G | + | [[Category: Gilliland, G L.]] |
[[Category: Ji, X.]] | [[Category: Ji, X.]] | ||
[[Category: Pechik, I.]] | [[Category: Pechik, I.]] | ||
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[[Category: oxygen transport]] | [[Category: oxygen transport]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:42:00 2008'' |
Revision as of 15:42, 21 February 2008
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OXYGEN AFFINITY MODULATION BY THE N-TERMINI OF THE BETA CHAINS IN HUMAN AND BOVINE HEMOGLOBIN
Contents |
Overview
A mutant human hemoglobin, beta (V1M+H2 delta), has been constructed. Analysis of the oxygen binding curves obtained at pH 8.3, where the Bohr effect is inoperative, indicates that this mutation results in an additional stabilization of the T-state conformation by 0.9 kcal/mol. The crystal structure of deoxy-beta (V1M+H2 delta) has been determined to 2.2-A resolution and compared with the deoxy structure of human hemoglobin at the same resolution. In human hemoglobin, a sulfate anion is anchored to the beta-chains by a complex network of H-bonds and electrostatic interactions with the amino terminus and Lys beta 82. In the mutant hemoglobin, the shortening of the amino-terminal region of the A helix by 1 residue results in the formation of an intrachain electrostatic interaction between the amino-terminal amino and Asp beta 79. This eliminates the sulfate binding site, and the sulfate is replaced by two water molecules. At variance with human hemoglobin, the alkaline Bohr effect for beta (V1M+H2 delta) is not sensitive to the presence of Cl-. This indicates that the sulfate binding site in human hemoglobin also serves as a Cl- binding site, and that the amino-terminal Val beta 1 is essential for oxygen-linked Cl- binding to hemoglobin as well as the Cl(-)-dependent Bohr effect. Analysis of the oxygen binding curves indicates that the oxygen-linked Cl- ions are released upon binding of the first oxygen molecule.
Disease
Known diseases associated with this structure: Erythremias, alpha- OMIM:[141800], Erythremias, beta- OMIM:[141900], Erythrocytosis OMIM:[141850], HPFH, deletion type OMIM:[141900], Heinz body anemia OMIM:[141850], Heinz body anemias, alpha- OMIM:[141800], Heinz body anemias, beta- OMIM:[141900], Hemoglobin H disease OMIM:[141850], Hypochromic microcytic anemia OMIM:[141850], Methemoglobinemias, alpha- OMIM:[141800], Methemoglobinemias, beta- OMIM:[141900], Sickle cell anemia OMIM:[141900], Thalassemia, alpha- OMIM:[141850], Thalassemia-beta, dominant inclusion-body OMIM:[141900], Thalassemias, alpha- OMIM:[141800], Thalassemias, beta- OMIM:[141900]
About this Structure
2HHE is a Protein complex structure of sequences from Homo sapiens with as ligand. Full crystallographic information is available from OCA.
Reference
Chloride ion independence of the Bohr effect in a mutant human hemoglobin beta (V1M+H2deleted)., Fronticelli C, Pechik I, Brinigar WS, Kowalczyk J, Gilliland GL, J Biol Chem. 1994 Sep 30;269(39):23965-9. PMID:7929044
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