1gvh: Difference between revisions

Revision as of 13:54, 21 February 2008

THE X-RAY STRUCTURE OF FERRIC ESCHERICHIA COLI FLAVOHEMOGLOBIN REVEALS AN UNESPECTED GEOMETRY OF THE DISTAL HEME POCKET

OverviewOverview

The x-ray structure of ferric unliganded lipid-free Escherichia coli flavohemoglobin has been solved to a resolution of 2.2 A and refined to an R-factor of 19%. The overall fold is similar to that of ferrous lipid-bound Alcaligenes eutrophus flavohemoglobin with the notable exception of the E helix positioning within the globin domain and a rotation of the NAD binding module with respect to the FAD-binding domain accompanied by a substantial rearrangement of the C-terminal region. An inspection of the heme environment in E. coli flavohemoglobin reveals an unexpected architecture of the distal pocket. In fact, the distal site is occupied by the isopropyl side chain Leu-E11 that shields the heme iron from the residues in the topological positions predicted to interact with heme iron-bound ligands, namely Tyr-B10 and Gln-E7, and stabilizes a pentacoordinate ferric iron species. Ligand binding properties are consistent with the presence of a pentacoordinate species in solution as indicated by a very fast second order combination rates with imidazole and azide. Surprisingly, imidazole, cyanide, and azide binding profiles at equilibrium are not accounted for by a single site titration curve but are biphasic and strongly suggest the presence of two distinct conformers within the liganded species.

About this StructureAbout this Structure

1GVH is a Single protein structure of sequence from Escherichia coli with , , and as ligands. Active as Transferred entry: 1.5.1.34, with EC number 1.6.99.7 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

The X-ray structure of ferric Escherichia coli flavohemoglobin reveals an unexpected geometry of the distal heme pocket., Ilari A, Bonamore A, Farina A, Johnson KA, Boffi A, J Biol Chem. 2002 Jun 28;277(26):23725-32. Epub 2002 Apr 18. PMID:11964402

Page seeded by OCA on Thu Feb 21 12:54:23 2008

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OCA

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 ==Overview==
-The x-ray structure of ferric unliganded lipid-free Escherichia coli, flavohemoglobin has been solved to a resolution of 2.2 A and refined to an, R-factor of 19%. The overall fold is similar to that of ferrous, lipid-bound Alcaligenes eutrophus flavohemoglobin with the notable, exception of the E helix positioning within the globin domain and a, rotation of the NAD binding module with respect to the FAD-binding domain, accompanied by a substantial rearrangement of the C-terminal region. An, inspection of the heme environment in E. coli flavohemoglobin reveals an, unexpected architecture of the distal pocket. In fact, the distal site is, occupied by the isopropyl side chain Leu-E11 that shields the heme iron, from the residues in the topological positions predicted to interact with, heme iron-bound ligands, namely Tyr-B10 and Gln-E7, and stabilizes a, pentacoordinate ferric iron species. Ligand binding properties are, consistent with the presence of a pentacoordinate species in solution as, indicated by a very fast second order combination rates with imidazole and, azide. Surprisingly, imidazole, cyanide, and azide binding profiles at, equilibrium are not accounted for by a single site titration curve but are, biphasic and strongly suggest the presence of two distinct conformers, within the liganded species.
+The x-ray structure of ferric unliganded lipid-free Escherichia coli flavohemoglobin has been solved to a resolution of 2.2 A and refined to an R-factor of 19%. The overall fold is similar to that of ferrous lipid-bound Alcaligenes eutrophus flavohemoglobin with the notable exception of the E helix positioning within the globin domain and a rotation of the NAD binding module with respect to the FAD-binding domain accompanied by a substantial rearrangement of the C-terminal region. An inspection of the heme environment in E. coli flavohemoglobin reveals an unexpected architecture of the distal pocket. In fact, the distal site is occupied by the isopropyl side chain Leu-E11 that shields the heme iron from the residues in the topological positions predicted to interact with heme iron-bound ligands, namely Tyr-B10 and Gln-E7, and stabilizes a pentacoordinate ferric iron species. Ligand binding properties are consistent with the presence of a pentacoordinate species in solution as indicated by a very fast second order combination rates with imidazole and azide. Surprisingly, imidazole, cyanide, and azide binding profiles at equilibrium are not accounted for by a single site titration curve but are biphasic and strongly suggest the presence of two distinct conformers within the liganded species.
 ==About this Structure==
@@ Line 13: / Line 13: @@
 [[Category: Escherichia coli]]
 [[Category: Single protein]]
-[[Category: Transferred entry: 1.5.1.34]]
+[[Category: Transferred entry: 1 5.1 34]]
 [[Category: Boffi, A.]]
 [[Category: Bonamore, A.]]
 [[Category: Farina, A.]]
 [[Category: Ilari, A.]]
-[[Category: Johnson, K.A.]]
+[[Category: Johnson, K A.]]
 [[Category: CL]]
 [[Category: FAD]]
@@ Line 30: / Line 30: @@
 [[Category: oxidoreductase]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb  3 09:43:06 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:54:23 2008''