4iro | pdb_00004iro

Crystal structure of T-state carbonmonoxy hemoglobin from Trematomus bernacchii at pH 8.4

spinqualitylabelsall models 4iro, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4iro is a 4 chain structure with sequence from Trematomus bernacchii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.2Å Ligands: ACE, CMO, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Many fish hemoglobins exhibit a marked dependence of oxygen affinity and cooperativity on proton concentration, called Root effect. Both tertiary and quaternary effects have been evoked to explain the allosteric regulation brought about by protons in fish hemoglobins. However, no general rules have emerged so far. We carried out a complementary crystallographic and microspectroscopic characterization of ligand binding to crystals of deoxy-hemoglobin from the Antarctic fish Trematomus bernacchii (HbTb) at pH6.2 and pH8.4. At low pH ligation has negligible structural effects, correlating with low affinity and absence of cooperativity in oxygen binding. At high pH, ligation causes significant changes at the tertiary structural level, while preserving structural markers of the T state. These changes mainly consist in a marked displacement of the position of the switch region CD corner towards an R-like position. The functional data on T-state crystals validate the relevance of the crystallographic observations, revealing that, differently from mammalian Hbs, in HbTb a significant degree of cooperativity in oxygen binding is due to tertiary conformational changes, in the absence of the T-R quaternary transition. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. Role of tertiary structures on the Root effect in fish hemoglobins.,Ronda L, Merlino A, Bettati S, Verde C, Balsamo A, Mazzarella L, Mozzarelli A, Vergara A Biochim Biophys Acta. 2013 Feb 1. pii: S1570-9639(13)00042-3. doi:, 10.1016/j.bbapap.2013.01.031. PMID:23376186 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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