1mrj: Difference between revisions
New page: left|200px<br /><applet load="1mrj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mrj, resolution 1.6Å" /> '''STUDIES ON CRYSTAL ST... |
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[[Image:1mrj.gif|left|200px]]<br /><applet load="1mrj" size=" | [[Image:1mrj.gif|left|200px]]<br /><applet load="1mrj" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1mrj, resolution 1.6Å" /> | caption="1mrj, resolution 1.6Å" /> | ||
'''STUDIES ON CRYSTAL STRUCTURES ACTIVE CENTER GEOMETRY AND DEPURINE MECHANISM OF TWO RIBOSOME-INACTIVATING PROTEINS'''<br /> | '''STUDIES ON CRYSTAL STRUCTURES ACTIVE CENTER GEOMETRY AND DEPURINE MECHANISM OF TWO RIBOSOME-INACTIVATING PROTEINS'''<br /> | ||
==Overview== | ==Overview== | ||
Two ribosome-inactivating proteins, trichosanthin and alpha-momorcharin, have been studied in the forms of complexes with ATP or formycin, by an | Two ribosome-inactivating proteins, trichosanthin and alpha-momorcharin, have been studied in the forms of complexes with ATP or formycin, by an X-ray-crystallographic method at 1.6-2.0 A (0.16-0.20 nm) resolution. The native alpha-momorcharin had been studied at 2.2 A resolution. Structures of trichosanthin were determined by a multiple isomorphous replacement method. Structures of alpha-momorcharin were determined by a molecular replacement method using refined trichosanthin as the searching model. Small ligands in all these complexes have been recognized and built on the difference in electron density. All these structures have been refined to achieve good results, both in terms of crystallography and of ideal geometry. These two proteins show considerable similarity in their three-dimensional folding and to that of related proteins. On the basis of these structures, detailed geometries of the active centres of these two proteins are described and are compared with those of related proteins. In all complexes the interactions between ligand atoms and protein atoms, including hydrophobic forces, aromatic stacking interactions and hydrogen bonds, are found to be specific towards the adenine base. The relationship between the sequence conservation of ribosome-inactivating proteins and their active-centre geometry was analysed. A depurinating mechanism of ribosome-inactivating proteins is proposed on the basis of these results. The N-7 atom of the substrate base group is proposed to be protonated by an acidic residue in the active centre. | ||
==About this Structure== | ==About this Structure== | ||
1MRJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Trichosanthes_kirilowii Trichosanthes kirilowii] with ADN as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | 1MRJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Trichosanthes_kirilowii Trichosanthes kirilowii] with <scene name='pdbligand=ADN:'>ADN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MRJ OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: ribosome-inactivating protein]] | [[Category: ribosome-inactivating protein]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:58:18 2008'' | ||
Revision as of 14:58, 21 February 2008
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STUDIES ON CRYSTAL STRUCTURES ACTIVE CENTER GEOMETRY AND DEPURINE MECHANISM OF TWO RIBOSOME-INACTIVATING PROTEINS
OverviewOverview
Two ribosome-inactivating proteins, trichosanthin and alpha-momorcharin, have been studied in the forms of complexes with ATP or formycin, by an X-ray-crystallographic method at 1.6-2.0 A (0.16-0.20 nm) resolution. The native alpha-momorcharin had been studied at 2.2 A resolution. Structures of trichosanthin were determined by a multiple isomorphous replacement method. Structures of alpha-momorcharin were determined by a molecular replacement method using refined trichosanthin as the searching model. Small ligands in all these complexes have been recognized and built on the difference in electron density. All these structures have been refined to achieve good results, both in terms of crystallography and of ideal geometry. These two proteins show considerable similarity in their three-dimensional folding and to that of related proteins. On the basis of these structures, detailed geometries of the active centres of these two proteins are described and are compared with those of related proteins. In all complexes the interactions between ligand atoms and protein atoms, including hydrophobic forces, aromatic stacking interactions and hydrogen bonds, are found to be specific towards the adenine base. The relationship between the sequence conservation of ribosome-inactivating proteins and their active-centre geometry was analysed. A depurinating mechanism of ribosome-inactivating proteins is proposed on the basis of these results. The N-7 atom of the substrate base group is proposed to be protonated by an acidic residue in the active centre.
About this StructureAbout this Structure
1MRJ is a Single protein structure of sequence from Trichosanthes kirilowii with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Studies on crystal structures, active-centre geometry and depurinating mechanism of two ribosome-inactivating proteins., Huang Q, Liu S, Tang Y, Jin S, Wang Y, Biochem J. 1995 Jul 1;309 ( Pt 1):285-98. PMID:7619070
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