1dgw
From Proteopedia
(New page: 200px<br /><applet load="1dgw" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dgw, resolution 1.7Å" /> '''Structure of the rhom...) |
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| - | [[Image:1dgw.jpg|left|200px]]<br /><applet load="1dgw" size=" | + | [[Image:1dgw.jpg|left|200px]]<br /><applet load="1dgw" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1dgw, resolution 1.7Å" /> | caption="1dgw, resolution 1.7Å" /> | ||
'''Structure of the rhombohedral crystal of canavalin from jack bean'''<br /> | '''Structure of the rhombohedral crystal of canavalin from jack bean'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The structure of canavalin, the vicilin-class storage protein from jack | + | The structure of canavalin, the vicilin-class storage protein from jack bean, was refined to 1.7 A resolution in a highly twinned rhombohedral crystal of space group R3 and unit-cell parameters a = b = c = 83.0 A, alpha = beta = gamma = 111.1 degrees. The resulting R and R(free) were 0.176 and 0.245, respectively. The orthorhombic crystal structure (space group C222(1), unit-cell parameters a = 136.5, b = 150.3, c = 133.4 A) was also refined with threefold non-crystallographic symmetry restraints. R and R(free) were 0.181 and 0.226, respectively, for 2.6 A resolution data. No significant difference in the protein structure was seen between these two crystal forms, nor between these two and the hexagonal and cubic crystal forms reported elsewhere [Ko et al. (1993), Acta Cryst. D49, 478-489; Ko et al. (1993), Plant Physiol. 101, 729-744]. A phosphate ion was identified in the lumen of the C-terminal beta-barrel. Lattice interactions showed that the trimeric molecule could be well accommodated in both 'top-up' and 'bottom-up' orientations in a rhombohedral unit cell of the R3 crystal and explained the presence of a high twin fraction. The large inter-trimer stacking interface of the C222(1) crystal may account for its relative stability. Atomic force microscopy (AFM) investigations of the growth of three crystal forms of canavalin indicate the rhombohedral form to be unique. Unlike the other two crystal forms, it contains at least an order of magnitude more screw dislocations and stacking faults than any other macromolecular crystal yet studied, and it alone grows principally by generation of steps from the screw dislocations. The unusually high occurrence of the screw dislocations and stacking faults is attributed to mechanical stress produced by the alternate molecular orientations in the rhombohedral crystals and their organization into discrete domains or blocks. At boundaries of alternate domains, lattice strain is relieved by the formation of the screw dislocations. |
==About this Structure== | ==About this Structure== | ||
| - | 1DGW is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Canavalia_ensiformis Canavalia ensiformis] with PO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1DGW is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Canavalia_ensiformis Canavalia ensiformis] with <scene name='pdbligand=PO4:'>PO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DGW OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Canavalia ensiformis]] | [[Category: Canavalia ensiformis]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Ko, T | + | [[Category: Ko, T P.]] |
[[Category: McPherson, A.]] | [[Category: McPherson, A.]] | ||
[[Category: PO4]] | [[Category: PO4]] | ||
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[[Category: merohedral/ hemihedral twinning]] | [[Category: merohedral/ hemihedral twinning]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:16:35 2008'' |
Revision as of 10:16, 21 February 2008
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Structure of the rhombohedral crystal of canavalin from jack bean
Overview
The structure of canavalin, the vicilin-class storage protein from jack bean, was refined to 1.7 A resolution in a highly twinned rhombohedral crystal of space group R3 and unit-cell parameters a = b = c = 83.0 A, alpha = beta = gamma = 111.1 degrees. The resulting R and R(free) were 0.176 and 0.245, respectively. The orthorhombic crystal structure (space group C222(1), unit-cell parameters a = 136.5, b = 150.3, c = 133.4 A) was also refined with threefold non-crystallographic symmetry restraints. R and R(free) were 0.181 and 0.226, respectively, for 2.6 A resolution data. No significant difference in the protein structure was seen between these two crystal forms, nor between these two and the hexagonal and cubic crystal forms reported elsewhere [Ko et al. (1993), Acta Cryst. D49, 478-489; Ko et al. (1993), Plant Physiol. 101, 729-744]. A phosphate ion was identified in the lumen of the C-terminal beta-barrel. Lattice interactions showed that the trimeric molecule could be well accommodated in both 'top-up' and 'bottom-up' orientations in a rhombohedral unit cell of the R3 crystal and explained the presence of a high twin fraction. The large inter-trimer stacking interface of the C222(1) crystal may account for its relative stability. Atomic force microscopy (AFM) investigations of the growth of three crystal forms of canavalin indicate the rhombohedral form to be unique. Unlike the other two crystal forms, it contains at least an order of magnitude more screw dislocations and stacking faults than any other macromolecular crystal yet studied, and it alone grows principally by generation of steps from the screw dislocations. The unusually high occurrence of the screw dislocations and stacking faults is attributed to mechanical stress produced by the alternate molecular orientations in the rhombohedral crystals and their organization into discrete domains or blocks. At boundaries of alternate domains, lattice strain is relieved by the formation of the screw dislocations.
About this Structure
1DGW is a Protein complex structure of sequences from Canavalia ensiformis with as ligand. Full crystallographic information is available from OCA.
Reference
X-ray diffraction and atomic force microscopy analysis of twinned crystals: rhombohedral canavalin., Ko TP, Kuznetsov YG, Malkin AJ, Day J, McPherson A, Acta Crystallogr D Biol Crystallogr. 2001 Jun;57(Pt 6):829-39. Epub 2001, May 25. PMID:11375502
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