1abr: Difference between revisions
New page: left|200px<br /><applet load="1abr" size="450" color="white" frame="true" align="right" spinBox="true" caption="1abr, resolution 2.14Å" /> '''CRYSTAL STRUCTURE OF... |
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[[Image:1abr.gif|left|200px]]<br /><applet load="1abr" size=" | [[Image:1abr.gif|left|200px]]<br /><applet load="1abr" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1abr, resolution 2.14Å" /> | caption="1abr, resolution 2.14Å" /> | ||
'''CRYSTAL STRUCTURE OF ABRIN-A'''<br /> | '''CRYSTAL STRUCTURE OF ABRIN-A'''<br /> | ||
==Overview== | ==Overview== | ||
The crystal structure of abrin-a, a type II ribosome-inactivating protein | The crystal structure of abrin-a, a type II ribosome-inactivating protein from the seeds of Abrus precatorius, has been determined from a novel crystalline form by the molecular replacement method using the coordinates of ricin. The structure has been refined at 2.14 A to a R-factor of 18.9%. The root-mean-square deviations of bond lengths and angles from the standard values are 0.013 A and 1.82 degrees, respectively. The overall protein folding is similar to that of ricin, but there are differences in the secondary structure, mostly of the A-chain. Several parts of the molecular surface differ significantly; some of them are quite near the active site cleft, and probably influence ribosome recognition. The positions of invariant active site residues remain the same, except the position of Tyr74. Two water molecules of hydrogen-bonded active site residues have been located in the active site cleft. Both of them may be responsible for hydrolyzing the N-C glycosidic bond. The current abrin-a structure is lactose free; this is probably essential for abrin-a crystallization. The B-chain is a glycoprotein, and the positions of several sugar residues of two sugar chains linked to earlier predicted glycosylation sites were determined. One of the sugar chains is a bridge between two neighboring molecules, since one of its mannose residues is connected to the galactose binding site of the neighboring molecule. Another sugar chain covers the surface of the B-chain. | ||
==About this Structure== | ==About this Structure== | ||
1ABR is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http:// | 1ABR is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ABR OCA]. | ||
==Reference== | ==Reference== | ||
Crystal structure of abrin-a at 2.14 A., Tahirov TH, Lu TH, Liaw YC, Chen YL, Lin JY, J Mol Biol. 1995 Jul 14;250(3):354-67. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7608980 7608980] | Crystal structure of abrin-a at 2.14 A., Tahirov TH, Lu TH, Liaw YC, Chen YL, Lin JY, J Mol Biol. 1995 Jul 14;250(3):354-67. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7608980 7608980] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Chu, S | [[Category: Chu, S C.]] | ||
[[Category: Liaw, Y | [[Category: Liaw, Y C.]] | ||
[[Category: Lin, J | [[Category: Lin, J Y.]] | ||
[[Category: Lu, T | [[Category: Lu, T H.]] | ||
[[Category: Tahirov, T | [[Category: Tahirov, T H.]] | ||
[[Category: complex (glycosidase/carbohydrate)]] | [[Category: complex (glycosidase/carbohydrate)]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:42:53 2008'' | ||
Revision as of 12:42, 21 February 2008
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CRYSTAL STRUCTURE OF ABRIN-A
OverviewOverview
The crystal structure of abrin-a, a type II ribosome-inactivating protein from the seeds of Abrus precatorius, has been determined from a novel crystalline form by the molecular replacement method using the coordinates of ricin. The structure has been refined at 2.14 A to a R-factor of 18.9%. The root-mean-square deviations of bond lengths and angles from the standard values are 0.013 A and 1.82 degrees, respectively. The overall protein folding is similar to that of ricin, but there are differences in the secondary structure, mostly of the A-chain. Several parts of the molecular surface differ significantly; some of them are quite near the active site cleft, and probably influence ribosome recognition. The positions of invariant active site residues remain the same, except the position of Tyr74. Two water molecules of hydrogen-bonded active site residues have been located in the active site cleft. Both of them may be responsible for hydrolyzing the N-C glycosidic bond. The current abrin-a structure is lactose free; this is probably essential for abrin-a crystallization. The B-chain is a glycoprotein, and the positions of several sugar residues of two sugar chains linked to earlier predicted glycosylation sites were determined. One of the sugar chains is a bridge between two neighboring molecules, since one of its mannose residues is connected to the galactose binding site of the neighboring molecule. Another sugar chain covers the surface of the B-chain.
About this StructureAbout this Structure
1ABR is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of abrin-a at 2.14 A., Tahirov TH, Lu TH, Liaw YC, Chen YL, Lin JY, J Mol Biol. 1995 Jul 14;250(3):354-67. PMID:7608980
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