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'''CRYSTAL STRUCTURE OF NITROPHORIN 4 FROM RHODNIUS PROLIXUS COMPLEXED WITH NITRIC OXIDE AT 1.08 A RESOLUTION''' | '''CRYSTAL STRUCTURE OF NITROPHORIN 4 FROM RHODNIUS PROLIXUS COMPLEXED WITH NITRIC OXIDE AT 1.08 A RESOLUTION''' | ||
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==About this Structure== | ==About this Structure== | ||
1KOI is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus]. This structure supersedes the now removed PDB entry | 1KOI is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=1ikh 1ikh]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KOI OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Walker, F A.]] | [[Category: Walker, F A.]] | ||
[[Category: Weichsel, A.]] | [[Category: Weichsel, A.]] | ||
[[Category: | [[Category: Anithistimine]] | ||
[[Category: | [[Category: Ferric heme]] | ||
[[Category: | [[Category: Lipocalin]] | ||
[[Category: | [[Category: Nitric oxide transport]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:59:06 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 22:59, 2 May 2008
CRYSTAL STRUCTURE OF NITROPHORIN 4 FROM RHODNIUS PROLIXUS COMPLEXED WITH NITRIC OXIDE AT 1.08 A RESOLUTION
OverviewOverview
The nitrophorins are a family of proteins that use ferric heme to transport nitric oxide (NO) from the salivary glands of blood-sucking insects to their victims, resulting in vasodilation and reduced blood coagulation. We have refined atomic resolution structures of nitrophorin 4 (NP4) from Rhodnius prolixus complexed with NO (1.08 A) and NH(3) (1.15 A), yielding a highly detailed picture of the iron coordination sphere. In NP4-NO, the NO nitrogen is coordinated to iron (Fe-N distance = 1.66 A) and is somewhat bent (Fe-N-O angle = 156 degrees ), with bending occurring in the same plane as the proximal histidine ring. The Fe(NO)(heme)(His) coordination geometry is unusual but consistent with an Fe(III) oxidation state that is stabilized by a highly ruffled heme. Heme ruffling occurs in both structures, apparently due to close contacts between the heme and leucines 123 and 133, but increases on binding NO even though the steric contacts have not changed. We also report the structure of NP4 in complexes with histamine (1.50 A) and imidazole (1.27 A). Unexpectedly, two mobile loops that rearrange to pack against the bound NO in NP4-NO, also rearrange in the NP4-imidazole complex. This conformational change is apparently driven by the nonpolar nature of the NO and imidazole (as bound) ligands. Taken together, the desolvation of the NO binding pocket through a change in protein conformation, and the bending of the NO moiety, possibly through protein-assisted heme ruffling, may lead to a nitrosyl-heme complex that is unusually resistant to autoreduction.
About this StructureAbout this Structure
1KOI is a Single protein structure of sequence from Rhodnius prolixus. This structure supersedes the now removed PDB entry 1ikh. Full crystallographic information is available from OCA.
ReferenceReference
Ligand-induced heme ruffling and bent no geometry in ultra-high-resolution structures of nitrophorin 4., Roberts SA, Weichsel A, Qiu Y, Shelnutt JA, Walker FA, Montfort WR, Biochemistry. 2001 Sep 25;40(38):11327-37. PMID:11560480 Page seeded by OCA on Fri May 2 22:59:06 2008