1dq1
From Proteopedia
(New page: 200px<br /><applet load="1dq1" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dq1, resolution 2.15Å" /> '''Calcium;Calcium conc...) |
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| - | [[Image:1dq1.gif|left|200px]]<br /><applet load="1dq1" size=" | + | [[Image:1dq1.gif|left|200px]]<br /><applet load="1dq1" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1dq1, resolution 2.15Å" /> | caption="1dq1, resolution 2.15Å" /> | ||
'''Calcium;Calcium concanavalin A'''<br /> | '''Calcium;Calcium concanavalin A'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The reversible binding of manganese and calcium to concanavalin A | + | The reversible binding of manganese and calcium to concanavalin A determines the carbohydrate binding of the lectin by inducing large conformational changes. These changes are governed by the isomerization of a non-proline peptide bond, Ala-207-Asp-208, positioned in a beta-strand in between the calcium binding site S2 and the carbohydrate specificity-determining loop. The replacement of calcium by manganese allowed us to investigate the structures of the carbohydrate binding, locked state and the inactive, unlocked state of concanavalin A, both with and without metal ions bound. Crystals of unlocked metal-free concanavalin A convert to the locked form with the binding of two Mn(2+) ions. Removal of these ions from the crystals traps metal-free concanavalin A in its locked state, a minority species in solution. The ligation of a metal ion in S2 to unlocked concanavalin A causes bending of the beta-strand foregoing the S2 ligand residues Asp-10 and Tyr-12. This bending disrupts conventional beta-sheet hydrogen bonding and forces the Thr-11 side chain against the Ala-207-Asp-208 peptide bond. The steric strain exerted by Thr-11 is presumed to drive the trans-to-cis isomerization. Upon isomerization, Asp-208 flips into its carbohydrate binding position, and the conformation of the carbohydrate specificity determining loop changes dramatically. |
==About this Structure== | ==About this Structure== | ||
| - | 1DQ1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Canavalia_ensiformis Canavalia ensiformis] with CA as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1DQ1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Canavalia_ensiformis Canavalia ensiformis] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DQ1 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: transition metal]] | [[Category: transition metal]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:19:14 2008'' |
Revision as of 10:19, 21 February 2008
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Calcium;Calcium concanavalin A
Overview
The reversible binding of manganese and calcium to concanavalin A determines the carbohydrate binding of the lectin by inducing large conformational changes. These changes are governed by the isomerization of a non-proline peptide bond, Ala-207-Asp-208, positioned in a beta-strand in between the calcium binding site S2 and the carbohydrate specificity-determining loop. The replacement of calcium by manganese allowed us to investigate the structures of the carbohydrate binding, locked state and the inactive, unlocked state of concanavalin A, both with and without metal ions bound. Crystals of unlocked metal-free concanavalin A convert to the locked form with the binding of two Mn(2+) ions. Removal of these ions from the crystals traps metal-free concanavalin A in its locked state, a minority species in solution. The ligation of a metal ion in S2 to unlocked concanavalin A causes bending of the beta-strand foregoing the S2 ligand residues Asp-10 and Tyr-12. This bending disrupts conventional beta-sheet hydrogen bonding and forces the Thr-11 side chain against the Ala-207-Asp-208 peptide bond. The steric strain exerted by Thr-11 is presumed to drive the trans-to-cis isomerization. Upon isomerization, Asp-208 flips into its carbohydrate binding position, and the conformation of the carbohydrate specificity determining loop changes dramatically.
About this Structure
1DQ1 is a Single protein structure of sequence from Canavalia ensiformis with as ligand. Full crystallographic information is available from OCA.
Reference
The structural features of concanavalin A governing non-proline peptide isomerization., Bouckaert J, Dewallef Y, Poortmans F, Wyns L, Loris R, J Biol Chem. 2000 Jun 30;275(26):19778-87. PMID:10748006
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