1apn
From Proteopedia
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| - | [[Image:1apn.gif|left|200px]] | + | [[Image:1apn.gif|left|200px]] |
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| - | '''THE CRYSTALLOGRAPHIC STRUCTURE OF METAL-FREE CONCANAVALIN A AT 2.5 ANGSTROMS RESOLUTION''' | + | {{Structure |
| + | |PDB= 1apn |SIZE=350|CAPTION= <scene name='initialview01'>1apn</scene>, resolution 2.5Å | ||
| + | |SITE= | ||
| + | |LIGAND= | ||
| + | |ACTIVITY= | ||
| + | |GENE= | ||
| + | }} | ||
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| + | '''THE CRYSTALLOGRAPHIC STRUCTURE OF METAL-FREE CONCANAVALIN A AT 2.5 ANGSTROMS RESOLUTION''' | ||
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==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1APN is a [ | + | 1APN is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Canavalia_ensiformis Canavalia ensiformis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1APN OCA]. |
==Reference== | ==Reference== | ||
| - | Crystallographic structure of metal-free concanavalin A at 2.5 A resolution., Bouckaert J, Loris R, Poortmans F, Wyns L, Proteins. 1995 Dec;23(4):510-24. PMID:[http:// | + | Crystallographic structure of metal-free concanavalin A at 2.5 A resolution., Bouckaert J, Loris R, Poortmans F, Wyns L, Proteins. 1995 Dec;23(4):510-24. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8749847 8749847] |
[[Category: Canavalia ensiformis]] | [[Category: Canavalia ensiformis]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: lectin]] | [[Category: lectin]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 10:00:41 2008'' |
Revision as of 08:00, 20 March 2008
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| Coordinates: | save as pdb, mmCIF, xml | ||||||
THE CRYSTALLOGRAPHIC STRUCTURE OF METAL-FREE CONCANAVALIN A AT 2.5 ANGSTROMS RESOLUTION
Overview
The three-dimensional structure of demetallized concanavalin A has been determined at 2.5 A resolution and refined to a crystallographic R-factor of 18%. The lectin activity of concanavalin A requires the binding of both a transition metal ion, generally Mn2+, and a Ca2+ ion in two neighboring sites in close proximity to the carbohydrate binding site. Large structural differences between the native and the metal-free lectin are observed in the metal-binding region and consequently for the residues involved in the specific binding of saccharides. The demetallization invokes a series of conformational changes in the protein backbone, apparently initiated mainly by the loss of the calcium ion. Most of the Mn2+ ligands retain their position, but the Ca2+ binding site is destroyed. The Ala207-Asp208 peptide bond, in the beta-strand neighboring the metal-binding sites, undergoes a cis to trans isomerization. The cis conformation for this bond is a highly conserved feature among the leguminous lectins and is critically maintained by the Ca2+ ion in metal-bound concanavalin A. A further and major change adjacent to the isomerized bond is an expansion of the loop containing the monosaccharide ligand residues Leu99 and Tyr100. The dispersion of the ligand residues for the monosaccharide binding site (Asn14, Agr228, Asp208, Leu99, and Tyr100) in metal-free concanavalin A abolishes the lectin's ability to bind saccharides. Since the quaternary structure of legume lectins is essential to their biological role, the tetramer formation was analyzed. In the crystal (pH 5), the metal-free concanavalin A dimers associate into a tetramer that is similar to the native one, but with a drastically reduced number of inter-dimer interactions. This explains the tetramer dissociation into dimers below pH values of 6.5.
About this Structure
1APN is a Single protein structure of sequence from Canavalia ensiformis. Full crystallographic information is available from OCA.
Reference
Crystallographic structure of metal-free concanavalin A at 2.5 A resolution., Bouckaert J, Loris R, Poortmans F, Wyns L, Proteins. 1995 Dec;23(4):510-24. PMID:8749847
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