1mep: Difference between revisions
New page: left|200px<br /><applet load="1mep" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mep, resolution 1.65Å" /> '''Crystal Structure of... |
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[[Image:1mep.gif|left|200px]]<br /><applet load="1mep" size=" | [[Image:1mep.gif|left|200px]]<br /><applet load="1mep" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1mep, resolution 1.65Å" /> | caption="1mep, resolution 1.65Å" /> | ||
'''Crystal Structure of Streptavidin Double Mutant S45A/D128A with Biotin: Cooperative Hydrogen-Bond Interactions in the Streptavidin-Biotin System.'''<br /> | '''Crystal Structure of Streptavidin Double Mutant S45A/D128A with Biotin: Cooperative Hydrogen-Bond Interactions in the Streptavidin-Biotin System.'''<br /> | ||
==Overview== | ==Overview== | ||
The thermodynamic and structural cooperativity between the Ser45- and | The thermodynamic and structural cooperativity between the Ser45- and D128-biotin hydrogen bonds was measured by calorimetric and X-ray crystallographic studies of the S45A/D128A double mutant of streptavidin. The double mutant exhibits a binding affinity approximately 2x10(7) times lower than that of wild-type streptavidin at 25 degrees C. The corresponding reduction in binding free energy (DeltaDeltaG) of 10.1 kcal/mol was nearly completely due to binding enthalpy losses at this temperature. The loss of binding affinity is 11-fold greater than that predicted by a linear combination of the single-mutant energetic perturbations (8.7 kcal/mol), indicating that these two mutations interact cooperatively. Crystallographic characterization of the double mutant and comparison with the two single mutant structures suggest that structural rearrangements at the S45 position, when the D128 carboxylate is removed, mask the true energetic contribution of the D128-biotin interaction. Taken together, the thermodynamic and structural analyses support the conclusion that the wild-type hydrogen bond between D128-OD and biotin-N2 is thermodynamically stronger than that between S45-OG and biotin-N1. | ||
==About this Structure== | ==About this Structure== | ||
1MEP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_avidinii Streptomyces avidinii] with BTN as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | 1MEP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_avidinii Streptomyces avidinii] with <scene name='pdbligand=BTN:'>BTN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MEP OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Streptomyces avidinii]] | [[Category: Streptomyces avidinii]] | ||
[[Category: Green, N | [[Category: Green, N M.]] | ||
[[Category: Hyre, D | [[Category: Hyre, D E.]] | ||
[[Category: Merritt, E | [[Category: Merritt, E A.]] | ||
[[Category: Stayton, P | [[Category: Stayton, P S.]] | ||
[[Category: Stenkamp, R | [[Category: Stenkamp, R E.]] | ||
[[Category: Trong, I | [[Category: Trong, I Le.]] | ||
[[Category: BTN]] | [[Category: BTN]] | ||
[[Category: biotin-binding protein]] | [[Category: biotin-binding protein]] | ||
[[Category: homotetramer]] | [[Category: homotetramer]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:54:30 2008'' | ||
Revision as of 14:54, 21 February 2008
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Crystal Structure of Streptavidin Double Mutant S45A/D128A with Biotin: Cooperative Hydrogen-Bond Interactions in the Streptavidin-Biotin System.
OverviewOverview
The thermodynamic and structural cooperativity between the Ser45- and D128-biotin hydrogen bonds was measured by calorimetric and X-ray crystallographic studies of the S45A/D128A double mutant of streptavidin. The double mutant exhibits a binding affinity approximately 2x10(7) times lower than that of wild-type streptavidin at 25 degrees C. The corresponding reduction in binding free energy (DeltaDeltaG) of 10.1 kcal/mol was nearly completely due to binding enthalpy losses at this temperature. The loss of binding affinity is 11-fold greater than that predicted by a linear combination of the single-mutant energetic perturbations (8.7 kcal/mol), indicating that these two mutations interact cooperatively. Crystallographic characterization of the double mutant and comparison with the two single mutant structures suggest that structural rearrangements at the S45 position, when the D128 carboxylate is removed, mask the true energetic contribution of the D128-biotin interaction. Taken together, the thermodynamic and structural analyses support the conclusion that the wild-type hydrogen bond between D128-OD and biotin-N2 is thermodynamically stronger than that between S45-OG and biotin-N1.
About this StructureAbout this Structure
1MEP is a Single protein structure of sequence from Streptomyces avidinii with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Cooperative hydrogen bond interactions in the streptavidin-biotin system., Hyre DE, Le Trong I, Merritt EA, Eccleston JF, Green NM, Stenkamp RE, Stayton PS, Protein Sci. 2006 Mar;15(3):459-67. Epub 2006 Feb 1. PMID:16452627
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