1dtm
From Proteopedia
(New page: 200px<br /> <applet load="1dtm" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dtm, resolution 2.13Å" /> '''CRYSTAL STRUCTURE O...) |
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caption="1dtm, resolution 2.13Å" /> | caption="1dtm, resolution 2.13Å" /> | ||
'''CRYSTAL STRUCTURE OF THE SPERM-WHALE MYOGLOBIN MUTANT H93G COMPLEXED WITH 4-METHYLIMIDAZOLE, METAQUO FORM'''<br /> | '''CRYSTAL STRUCTURE OF THE SPERM-WHALE MYOGLOBIN MUTANT H93G COMPLEXED WITH 4-METHYLIMIDAZOLE, METAQUO FORM'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The structural role of a side-chain to side-chain protein hydrogen bond is | + | The structural role of a side-chain to side-chain protein hydrogen bond is examined using trans-substitution of the proximal histidine of myoglobin with methylimidazoles (Barrick, Biochemistry 1994;33:6546-6554). Modification of the chemical structure of exogenous ligands allows this hydrogen bond to be disrupted. Comparison of the crystal structures of H93G myoglobin complexed 4-methylimidazole (4meimd; methylation at carbon 4) and 1-methylimidazole (1meimd; methylation at the adjacent nitrogen, preventing hydrogen bonding between the imidazole ligand and the protein) shows that the polypeptide, heme, and methylimidazole orientations are the same within error. For 4meimd there appear to be major and minor conformations corresponding to different tautomeric states of the ligand. Conformational heterogeneity is also seen in the hyperfine-shifted region of the NMR spectrum of 4meimd complexed with high-spin H93G deoxyMb. The major conformation of the 4meimd ligand and the 1meimd ligand, as seen in the respective crystal structures, are quite similar except that the proximal ligand NH-to-Ser92-OH hydrogen bond is eliminated in the 1meimd complex, and instead the proximal ligand CH is adjacent to the Ser92-OH. Thus, this system provides a means to eliminate the Mb proximal hydrogen bond in a chemically and structurally conservative way. |
==About this Structure== | ==About this Structure== | ||
| - | 1DTM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Physeter_catodon Physeter catodon] with HEM and 4MZ as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1DTM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Physeter_catodon Physeter catodon] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=4MZ:'>4MZ</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DTM OCA]. |
==Reference== | ==Reference== | ||
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[[Category: myoglobin]] | [[Category: myoglobin]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:20:19 2008'' |
Revision as of 10:20, 21 February 2008
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CRYSTAL STRUCTURE OF THE SPERM-WHALE MYOGLOBIN MUTANT H93G COMPLEXED WITH 4-METHYLIMIDAZOLE, METAQUO FORM
Overview
The structural role of a side-chain to side-chain protein hydrogen bond is examined using trans-substitution of the proximal histidine of myoglobin with methylimidazoles (Barrick, Biochemistry 1994;33:6546-6554). Modification of the chemical structure of exogenous ligands allows this hydrogen bond to be disrupted. Comparison of the crystal structures of H93G myoglobin complexed 4-methylimidazole (4meimd; methylation at carbon 4) and 1-methylimidazole (1meimd; methylation at the adjacent nitrogen, preventing hydrogen bonding between the imidazole ligand and the protein) shows that the polypeptide, heme, and methylimidazole orientations are the same within error. For 4meimd there appear to be major and minor conformations corresponding to different tautomeric states of the ligand. Conformational heterogeneity is also seen in the hyperfine-shifted region of the NMR spectrum of 4meimd complexed with high-spin H93G deoxyMb. The major conformation of the 4meimd ligand and the 1meimd ligand, as seen in the respective crystal structures, are quite similar except that the proximal ligand NH-to-Ser92-OH hydrogen bond is eliminated in the 1meimd complex, and instead the proximal ligand CH is adjacent to the Ser92-OH. Thus, this system provides a means to eliminate the Mb proximal hydrogen bond in a chemically and structurally conservative way.
About this Structure
1DTM is a Single protein structure of sequence from Physeter catodon with and as ligands. Full crystallographic information is available from OCA.
Reference
Trans-substitution of the proximal hydrogen bond in myoglobin: I. Structural consequences of hydrogen bond deletion., Barrick D, Dahlquist FW, Proteins. 2000 Jun 1;39(4):278-90. PMID:10813811
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