1cax
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(New page: 200px<br /><applet load="1cax" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cax, resolution 2.6Å" /> '''DETERMINATION OF THRE...)
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Revision as of 10:11, 20 November 2007
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DETERMINATION OF THREE CRYSTAL STRUCTURES OF CANAVALIN BY MOLECULAR REPLACEMENT
Overview
Canavalin, the major reserve protein of the jack bean, was obtained in, four different crystal forms. From the structure determined by multiple, isomorphous replacement in a hexagonal unit cell, the structures of three, other crystals were determined by molecular replacement. In two cases, the, rhombohedral and cubic crystals, placement was facilitated by coincidence, of threefold molecular symmetry with crystallographic operators. In the, orthorhombic crystal the canavalin trimer was the asymmetric unit. The, rhombohedral, orthorhombic and cubic crystal structures were subsequently, refined using a combination of several approaches with resulting R factors, of 0.194, 0.185 and 0.211 at resolutions of 2.6, 2.6 and 2.3 A, respectively. Variation in the conformation of the molecule from crystal, to crystal was small with an r.m.s. deviation in Calpha positions of 0.89, A. Packing is quite different among crystal forms but lattice interactions, appear to play little role in the conformation of the molecule. Greatest, variations in mean position are for those residues that also exhibit the, greatest thermal motion. Crystal contacts in all crystals are mediated, almost exclusively by hydrophilic side chains, and three to six, intermolecular salt bridges per protein subunit are present in each case.
About this Structure
1CAX is a Protein complex structure of sequences from Canavalia ensiformis. Full crystallographic information is available from OCA.
Reference
Determination of three crystal structures of canavalin by molecular replacement., Ko TP, Ng JD, Greenwood A, McPherson A, Acta Crystallogr D Biol Crystallogr. 1993 Sep 1;49(Pt 5):478-89. PMID:15299507
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