1u0x: Difference between revisions
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[[Image:1u0x.jpg|left|200px]]<br /><applet load="1u0x" size=" | [[Image:1u0x.jpg|left|200px]]<br /><applet load="1u0x" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1u0x, resolution 1.45Å" /> | caption="1u0x, resolution 1.45Å" /> | ||
'''Crystal structure of nitrophorin 4 under pressure of xenon (200 psi)'''<br /> | '''Crystal structure of nitrophorin 4 under pressure of xenon (200 psi)'''<br /> | ||
==Overview== | ==Overview== | ||
Nitrophorin 4 (NP4) is one of seven nitric oxide (NO) transporting | Nitrophorin 4 (NP4) is one of seven nitric oxide (NO) transporting proteins in the blood-sucking insect Rhodnius prolixus. In its physiological function, NO binds to a ferric iron centered in a highly ruffled heme plane. Carbon monoxide (CO) also binds after reduction of the heme iron. Here we have used Fourier transform infrared spectroscopy at cryogenic temperatures to study CO and NO binding and migration in NP4, complemented by x-ray cryo-crystallography on xenon-containing NP4 crystals to identify cavities that may serve as ligand docking sites. Multiple infrared stretching bands of the heme-bound ligands indicate different active site conformations with varying degrees of hydrophobicity. Narrow infrared stretching bands are observed for photodissociated CO and NO; temperature-derivative spectroscopy shows that these bands are associated with ligand docking sites close to the extremely reactive heme iron. No rebinding from distinct secondary sites was detected, although two xenon binding cavities were observed in the x-ray structure. Photolysis studies at approximately 200 K show efficient NO photoproduct formation in the more hydrophilic, open NP4 conformation. This result suggests that ligand escape is facilitated in this conformation, and blockage of the active site by water hinders immediate reassociation of NO to the ferric iron. In the closed, low-pH conformation, ligand escape from the active site of NP4 is prevented by an extremely reactive heme iron and the absence of secondary ligand docking sites. | ||
==About this Structure== | ==About this Structure== | ||
1U0X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus] with HEM, NH3 and XE as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1U0X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus] with <scene name='pdbligand=HEM:'>HEM</scene>, <scene name='pdbligand=NH3:'>NH3</scene> and <scene name='pdbligand=XE:'>XE</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1U0X OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Rhodnius prolixus]] | [[Category: Rhodnius prolixus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Maes, E | [[Category: Maes, E M.]] | ||
[[Category: Montfort, W | [[Category: Montfort, W R.]] | ||
[[Category: Nienhaus, G | [[Category: Nienhaus, G U.]] | ||
[[Category: Nienhaus, K.]] | [[Category: Nienhaus, K.]] | ||
[[Category: Weichsel, A.]] | [[Category: Weichsel, A.]] | ||
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[[Category: xenon]] | [[Category: xenon]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:19:32 2008'' | ||
Revision as of 16:19, 21 February 2008
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Crystal structure of nitrophorin 4 under pressure of xenon (200 psi)
OverviewOverview
Nitrophorin 4 (NP4) is one of seven nitric oxide (NO) transporting proteins in the blood-sucking insect Rhodnius prolixus. In its physiological function, NO binds to a ferric iron centered in a highly ruffled heme plane. Carbon monoxide (CO) also binds after reduction of the heme iron. Here we have used Fourier transform infrared spectroscopy at cryogenic temperatures to study CO and NO binding and migration in NP4, complemented by x-ray cryo-crystallography on xenon-containing NP4 crystals to identify cavities that may serve as ligand docking sites. Multiple infrared stretching bands of the heme-bound ligands indicate different active site conformations with varying degrees of hydrophobicity. Narrow infrared stretching bands are observed for photodissociated CO and NO; temperature-derivative spectroscopy shows that these bands are associated with ligand docking sites close to the extremely reactive heme iron. No rebinding from distinct secondary sites was detected, although two xenon binding cavities were observed in the x-ray structure. Photolysis studies at approximately 200 K show efficient NO photoproduct formation in the more hydrophilic, open NP4 conformation. This result suggests that ligand escape is facilitated in this conformation, and blockage of the active site by water hinders immediate reassociation of NO to the ferric iron. In the closed, low-pH conformation, ligand escape from the active site of NP4 is prevented by an extremely reactive heme iron and the absence of secondary ligand docking sites.
About this StructureAbout this Structure
1U0X is a Single protein structure of sequence from Rhodnius prolixus with , and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Structural dynamics controls nitric oxide affinity in nitrophorin 4., Nienhaus K, Maes EM, Weichsel A, Montfort WR, Nienhaus GU, J Biol Chem. 2004 Sep 17;279(38):39401-7. Epub 2004 Jul 16. PMID:15258143
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