1ith: Difference between revisions
New page: left|200px<br /> <applet load="1ith" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ith, resolution 2.5Å" /> '''STRUCTURE DETERMINAT... |
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[[Image:1ith.gif|left|200px]]<br /> | [[Image:1ith.gif|left|200px]]<br /><applet load="1ith" size="350" color="white" frame="true" align="right" spinBox="true" | ||
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caption="1ith, resolution 2.5Å" /> | caption="1ith, resolution 2.5Å" /> | ||
'''STRUCTURE DETERMINATION AND REFINEMENT OF HOMOTETRAMERIC HEMOGLOBIN FROM URECHIS CAUPO AT 2.5 ANGSTROMS RESOLUTION'''<br /> | '''STRUCTURE DETERMINATION AND REFINEMENT OF HOMOTETRAMERIC HEMOGLOBIN FROM URECHIS CAUPO AT 2.5 ANGSTROMS RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
A 5 A resolution multiple isomorphous replacement solution for hemoglobin | A 5 A resolution multiple isomorphous replacement solution for hemoglobin isolated from Urechis caupo revealed a previously unobserved quaternary structure for tetrameric hemoglobin [Kolatkar, Meador, Stanfield & Hackert (1988). J. Biol. Chem. 263(7), 3462-3465]. We report here the structure of Urechis hemoglobin in the cyanomet state refined to 2.5 A resolution by simulated annealing yielding R = 0.148 for reflections F greater than 3 sigma between 5.0 and 2.5 A resolution. The starting model was fitted to a map originally derived from multiple-wavelength anomalous-dispersion phases to 3 A resolution that was then subjected to cyclic twofold molecular averaging and solvent flattening. Structural analysis of the resultant model shows that the unique quaternary assemblage is possible due to several favorable interactions between subunits, including salt links, hydrophobic pockets and interactions mediated by bound water. The tetramer is stabilized by subunit-subunit interactions between the G/H turns and D helices within the crystallographic dimer, and the A/B turn regions and E helices between subunits related by a molecular twofold axis. Interestingly, each subunit has one cysteine residue (Cys21) located in the A/B turn. These twofold-related cysteinyl residues are near enough to one another to form a disulfide bridge but do not. | ||
==About this Structure== | ==About this Structure== | ||
1ITH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Urechis_caupo Urechis caupo] with CYN and HEM as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1ITH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Urechis_caupo Urechis caupo] with <scene name='pdbligand=CYN:'>CYN</scene> and <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ITH OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Urechis caupo]] | [[Category: Urechis caupo]] | ||
[[Category: Ernst, S | [[Category: Ernst, S R.]] | ||
[[Category: Hackert, M.]] | [[Category: Hackert, M.]] | ||
[[Category: Hendrickson, W | [[Category: Hendrickson, W A.]] | ||
[[Category: Kolatkar, P.]] | [[Category: Kolatkar, P.]] | ||
[[Category: Merritt, E | [[Category: Merritt, E A.]] | ||
[[Category: Ogata, C | [[Category: Ogata, C M.]] | ||
[[Category: Phizackerley, R | [[Category: Phizackerley, R P.]] | ||
[[Category: CYN]] | [[Category: CYN]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
[[Category: oxygen transport]] | [[Category: oxygen transport]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:15:30 2008'' | ||
Revision as of 14:15, 21 February 2008
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STRUCTURE DETERMINATION AND REFINEMENT OF HOMOTETRAMERIC HEMOGLOBIN FROM URECHIS CAUPO AT 2.5 ANGSTROMS RESOLUTION
OverviewOverview
A 5 A resolution multiple isomorphous replacement solution for hemoglobin isolated from Urechis caupo revealed a previously unobserved quaternary structure for tetrameric hemoglobin [Kolatkar, Meador, Stanfield & Hackert (1988). J. Biol. Chem. 263(7), 3462-3465]. We report here the structure of Urechis hemoglobin in the cyanomet state refined to 2.5 A resolution by simulated annealing yielding R = 0.148 for reflections F greater than 3 sigma between 5.0 and 2.5 A resolution. The starting model was fitted to a map originally derived from multiple-wavelength anomalous-dispersion phases to 3 A resolution that was then subjected to cyclic twofold molecular averaging and solvent flattening. Structural analysis of the resultant model shows that the unique quaternary assemblage is possible due to several favorable interactions between subunits, including salt links, hydrophobic pockets and interactions mediated by bound water. The tetramer is stabilized by subunit-subunit interactions between the G/H turns and D helices within the crystallographic dimer, and the A/B turn regions and E helices between subunits related by a molecular twofold axis. Interestingly, each subunit has one cysteine residue (Cys21) located in the A/B turn. These twofold-related cysteinyl residues are near enough to one another to form a disulfide bridge but do not.
About this StructureAbout this Structure
1ITH is a Single protein structure of sequence from Urechis caupo with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Structure determination and refinement of homotetrameric hemoglobin from Urechis caupo at 2.5 A resolution., Kolatkar PR, Ernst SR, Hackert ML, Ogata CM, Hendrickson WA, Merritt EA, Phizackerley RP, Acta Crystallogr B. 1992 Apr 1;48 ( Pt 2):191-9. PMID:1515107
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