2g3h

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Revision as of 11:23, 8 November 2007

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spinqualitylabelsall models 2g3h, resolution 1.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Cyanide Binding and Heme Cavity Conformational Transitions in Drosophila melanogaster Hexa-coordinate Hemoglobin

Overview

The reason for the presence of hemoglobin-like molecules in insects, such, as Drosophila melanogaster, that live in fully aerobic environments has, yet to be determined. Heme endogenous hexacoordination (where HisE7 and, HisF8 axial ligands to the heme Fe atom are both provided by the protein), is a recently discovered mechanism proposed to modulate O(2) affinity in, hemoglobins from different species. Previous results have shown that D., melanogaster hemoglobin 1 (product of the glob1 gene) displays heme, endogenous hexacoordination in both the ferrous and ferric states. Here we, present kinetic data characterizing the exogenous cyanide ligand binding, process, and the three-dimensional structure (at 1.4 A resolution) of the, ensuing cyano-met D. melanogaster hemoglobin. Comparison with the crystal, structure of the endogenously hexacoordinated D. melanogaster hemoglobin, shows that the transition to the cyano-met form is supported by, conformational readjustment in the CD-D-E region of the protein, which, removes HisE7 from the heme. The structural and functional features of D., melanogaster hemoglobin are examined in light of previous results achieved, for human and mouse neuroglobins and for human cytoglobin, which display, heme endogenous hexacoordination. The study shows that, despite the rather, constant value for cyanide association rate constants for the ferric, hemoproteins, different distal site conformational readjustments and/or, heme sliding mechanisms are displayed by the known hexacoordinate, hemoglobins as a result of exogenous ligand binding.

About this Structure

2G3H is a Single protein structure of sequence from Drosophila melanogaster with CL, MG, CYN and HEM as ligands. Full crystallographic information is available from OCA.

Reference

Cyanide binding and heme cavity conformational transitions in Drosophila melanogaster hexacoordinate hemoglobin., de Sanctis D, Ascenzi P, Bocedi A, Dewilde S, Burmester T, Hankeln T, Moens L, Bolognesi M, Biochemistry. 2006 Aug 22;45(33):10054-61. PMID:16906763

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