1qdc
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MAN(APLHA1-6)MAN(ALPHA1-O)METHYL CONCANAVALIN A COMPLEX
OverviewOverview
The crystal structures of concanavalin A in complex with, Man(alpha1-6)Man(alpha1-O)Me and Man(alpha1-3)Man(alpha1-O)Me were, determined at resolutions of 2.0 and 2.8 A, respectively. In both, structures, the O-1-linked mannose binds in the conserved, monosaccharide-binding site. The O-3-linked mannose of, Man(alpha1-3)Man(alpha1-O)Me binds in the hydrophobic subsite formed by, Tyr-12, Tyr-100, and Leu-99. The shielding of a hydrophobic surface is, consistent with the associated large heat capacity change. The O-6-linked, mannose of Man(alpha1-6)Man(alpha1-O)Me binds in the same subsite formed, by Tyr-12 and Asp-16 as the reducing mannose of the highly specific, trimannose Man(alpha1-3)[Man(alpha1-6)]Man(alpha1-O)Me. However, it is, much less tightly bound. Its O-2 hydroxyl makes no hydrogen bond with the, conserved water 1. Water 1 is present in all the sugar-containing, concanavalin A structures and increases the complementarity between the, protein-binding surface and the sugar, but is not necessarily a, hydrogen-bonding partner. A water analysis of the carbohydrate-binding, site revealed a conserved water molecule replacing O-4 on the, alpha1-3-linked arm of the trimannose. No such water is found for the, reducing or O-6-linked mannose. Our data indicate that the central mannose, of Man(alpha1-3)[Man(alpha1-6)]Man(alpha1-O)Me primarily functions as a, hinge between the two outer subsites.
About this StructureAbout this Structure
1QDC is a Single protein structure of sequence from Canavalia ensiformis with MN, CA and CL as ligands. Full crystallographic information is available from OCA.
ReferenceReference
The crystal structures of Man(alpha1-3)Man(alpha1-O)Me and Man(alpha1-6)Man(alpha1-O)Me in complex with concanavalin A., Bouckaert J, Hamelryck TW, Wyns L, Loris R, J Biol Chem. 1999 Oct 8;274(41):29188-95. PMID:10506175
Page seeded by OCA on Wed Nov 21 00:35:45 2007