2c0k
From Proteopedia
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THE STRUCTURE OF HEMOGLOBIN FROM THE BOTFLY GASTEROPHILUS INTESTINALIS
Overview
Hemoglobins (Hbs) reversibly bind gaseous diatomic ligands (e.g., O2) as, the sixth heme axial ligand of the penta-coordinate deoxygenated form., Selected members of the Hb superfamily, however, display a functionally, relevant hexa-coordinate heme Fe atom in their deoxygenated state., Endogenous heme hexa-coordination is generally provided in these Hbs by, the E7 residue (often His), which thus modulates accessibility to the heme, distal pocket and reactivity of the heme toward exogenous ligands. Such a, pivotal role of the E7 residue is prominently shown by analysis of the, functional and structural properties of insect Hbs. Here, we report the, 2.6 A crystal structure of oxygenated Gasterophilus intestinalis Hb1, a Hb, known to display a penta-coordinate heme in the deoxygenated form. The, structure is analyzed in comparison with those of Drosophila melanogaster, Hb, exhibiting a hexa-coordinate heme in its deoxygenated derivative, and, of Chironomus thummi thummi HbIII, which displays a penta-coordinate heme, in the deoxygenated form. Despite evident structural differences in the, heme distal pockets, the distinct molecular mechanisms regulating O2, binding to the three insect Hbs result in similar O(2 affinities (P50, values ranging between 0.12 torr and 0.46 torr).
About this Structure
2C0K is a Single protein structure of sequence from Gasterophilus intestinalis with and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Modulation of oxygen binding to insect hemoglobins: the structure of hemoglobin from the botfly Gasterophilus intestinalis., Pesce A, Nardini M, Dewilde S, Hoogewijs D, Ascenzi P, Moens L, Bolognesi M, Protein Sci. 2005 Dec;14(12):3057-63. Epub 2005 Oct 31. PMID:16260762
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