1hlb

Structural analysis of monomeric hemichrome and dimeric cyanomet hemoglobins from Caudina arenicola

spinqualitylabelsall models 1hlb, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1hlb is a 1 chain structure with sequence from Molpadia arenicola. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.5Å Ligands: ACE, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function GLBC_MOLAR Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The X-ray structures of two hemoglobins (Hb) from the sea cucumber Caudina arenicola (an echinoderm) have been determined: a low spin, hemichrome, monomeric Hb-C chain, and a cyanomet-liganded dimeric Hb-D chain. Attempts to obtain crystal structures of the deoxy-liganded and hemichrome forms from the same chain type have not been successful. In this work, the Hb-C chain and Hb-D chain structures are compared, and differences observed in tertiary structure related to the different ligand states for hemoglobin chains from this organism. In addition to shifts of the distal histidine and E helix, differences are noted in the position of the heme group within the heme pocket, the hydrogen bonding of the heme group to the protein, and the status of the D helix. These differences are important in understanding the ligand-linked association states of these hemoglobins. The quaternary structure of the Hb-D homodimer is compared with those from two other invertebrate hemoglobins from Scapharca inaequivalvis and Urechis caupo, which also have subunit-subunit interactions that involve the E and E' helices. The dimer interactions of the Caudina and Urechis hemoglobins are quite dissimilar. However, the dimer interface observed in cyanomet Hb-D is strikingly similar to that observed for the carbonmonoxy hemoglobin dimer from the clam, Scapharca, yet many of the key amino acid residues implicated in the cooperative mechanism of the Scapharca hemoglobin are not conserved in the Caudina hemoglobins. Structural analysis of monomeric hemichrome and dimeric cyanomet hemoglobins from Caudina arenicola.,Mitchell DT, Kitto GB, Hackert ML J Mol Biol. 1995 Aug 18;251(3):421-31. PMID:7650740 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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