4hrr

Scapharca tetrameric hemoglobin, CO-state

spinqualitylabelsall models 4hrr, resolution 1.25Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4hrr is a 8 chain structure with sequence from Anadara inaequivalvis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.25Å Ligands: ACE, CMO, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function GLB2A_ANAIN Publication Abstract from PubMed The clam Scapharca inaequivalvis possesses two cooperative oxygen binding hemoglobins in its red cells: a homodimeric HbI and a heterotetrameric A2B2 HbII. Each AB dimeric half of HbII is assembled in a manner very similar to that of the well-studied HbI. This study presents crystal structures of HbII along with oxygen binding data both in the crystalline state and in wet nanoporous silica gels. Despite very similar ligand-linked structural transitions observed in HbI and HbII crystals, HbII in the crystal or encapsulated in silica gels apparently exhibits minimal cooperativity in oxygen binding, in contrast with the full cooperativity exhibited by HbI crystals. However, oxygen binding curves in the crystal indicate the presence of a significant functional inequivalence of A and B chains. When this inequivalence is taken into account, both crystal and R state gel functional data are consistent with the conservation of a tertiary contribution to cooperative oxygen binding, quantitatively similar to that measured for HbI, and are in keeping with the structural information. Furthermore, our results indicate that to fully express cooperative ligand binding, HbII requires quaternary transitions hampered by crystal lattice and gel encapsulation, revealing greater complexity in cooperative function than the direct communication across a dimeric interface observed in HbI. Tertiary and Quaternary Allostery in Tetrameric Hemoglobin from Scapharca inaequivalvis.,Ronda L, Bettati S, Henry ER, Kashav T, Sanders JM, Royer WE, Mozzarelli A Biochemistry. 2013 Mar 15. PMID:23458680 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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