4sdh

<StructureSection load='4sdh' size='340' side='right' caption='[[4sdh]], [[Resolution|resolution]] 1.60&Aring;' scene=''>

<table><tr><td colspan='2'>[[4sdh]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Scapharca_inaequivalvis Scapharca inaequivalvis]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=2sdh 2sdh]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4SDH OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4SDH FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4sdh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4sdh OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4sdh RCSB], [http://www.ebi.ac.uk/pdbsum/4sdh PDBsum]</span></td></tr>

<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/sd/4sdh_consurf.spt"</scriptWhenChecked>

</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].

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== Publication Abstract from PubMed ==

High-resolution crystal structures of the co-operative dimeric hemoglobin from the blood clam Scapharca inaequivalvis have been determined in the unliganded (deoxy) and carbon monoxide (CO) liganded states. The deoxy structure has been refined at 1.6 A resolution to an R-factor of 0.158 and the CO structure has been refined at 1.4 A resolution to an R-factor of 0.159. These structures reveal details of the structural transitions involved in co-operative ligand binding that involve only a minor rotation of subunits but very striking tertiary changes at the interface. A small number of residues in the F-helix appear to mediate co-operativity in this simple hemoglobin. The oxygen affinity of each subunit appears to be largely dictated by the disposition of phenylalanine 97, whose side-chain packs in the heme pocket in the deoxy state but is extruded towards the interface in the CO-liganded structure. Direct involvement of the ligand-binding heme group is a novel feature of the subunit interface and appears important for intersubunit communication. Ligation alters the conformation of the heme propionate groups along with two interacting residues from the symmetry-related subunit. These two residues, lysine 96 and asparagine 100, link the heme of one subunit with the F-helix of the second subunit in such a way as to influence the ligand affinity of that subunit. The interface is highly hydrated by well-ordered water molecules that are likely to be important in the stabilization of the two structures.

High-resolution crystallographic analysis of a co-operative dimeric hemoglobin.,Royer WE Jr J Mol Biol. 1994 Jan 14;235(2):657-81. PMID:8289287<ref>PMID:8289287</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Scapharca inaequivalvis]]

[[Category: Royerjunior, W E]]

[[Category: Oxygen transport]]