4sdh: Difference between revisions
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{{STRUCTURE_4sdh| PDB=4sdh | SCENE= }} | |||
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'''HIGH RESOLUTION CRYSTALLOGRAPHIC ANALYSIS OF A COOPERATIVE DIMERIC HEMOGLOBIN''' | '''HIGH RESOLUTION CRYSTALLOGRAPHIC ANALYSIS OF A COOPERATIVE DIMERIC HEMOGLOBIN''' | ||
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==About this Structure== | ==About this Structure== | ||
4SDH is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Scapharca_inaequivalvis Scapharca inaequivalvis]. This structure supersedes the now removed PDB entry | 4SDH is a [[Single protein]] structure of 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]. | ||
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Royerjunior, W E.]] | [[Category: Royerjunior, W E.]] | ||
[[Category: | [[Category: Oxygen transport]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 22:29:22 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 19:29, 4 May 2008
HIGH RESOLUTION CRYSTALLOGRAPHIC ANALYSIS OF A COOPERATIVE DIMERIC HEMOGLOBIN
Overview
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.
About this Structure
4SDH is a Single protein structure of sequence from Scapharca inaequivalvis. This structure supersedes the now removed PDB entry 2sdh. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Sun May 4 22:29:22 2008
