2enr
CO-CRYSTALS OF DEMETALLIZED CONCANAVALIN A WITH CADMIUM HAVING A CADMIUM ION BOUND IN BOTH THE S1 SITE AND THE S2 SITE
OverviewOverview
The crystal structures of cadmium/cadmium and zinc/calcium concanavalin A (con A) at pH 5.0 and pH 6.15, respectively, were determined. The structure of cadmium/cadmium con A confirms that the secondary Cd(2+)-binding site S3 is empty at pH 5. The metal-binding sites S1 and S2 are only very slightly affected by the substitution with cadmium. On the other hand, S1 and S2 and most of the protein surface of zinc/calcium con A at pH 6.15 differ from other fully metal-bound and carbohydrate-free structures. Most of these structural differences at the protein surface are a result of the interplay between metal binding, protonation and crystal packing. This interplay is expressed by relative rotations and translations of the con A units in alternative crystal packings and participation in space-group conversions inside crystals in situ. The particular crystal packing of zinc/calcium con A creates a novel zinc-binding site S4. The Zn(2+) ion in S4 ligates two aspartates from one tetramer and a histidine from a symmetry-related tetramer.
About this StructureAbout this Structure
2ENR is a Single protein structure of sequence from Canavalia ensiformis. Full crystallographic information is available from OCA.
ReferenceReference
Zinc/calcium- and cadmium/cadmium-substituted concanavalin A: interplay of metal binding, pH and molecular packing., Bouckaert J, Loris R, Wyns L, Acta Crystallogr D Biol Crystallogr. 2000 Dec;56(Pt 12):1569-76. PMID:11092923 Page seeded by OCA on Sun May 4 02:51:17 2008