1m9p
From Proteopedia
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Crystalline Human Carbonmonoxy Hemoglobin C Exhibits The R2 Quaternary State at Neutral pH In The Presence of Polyethylene Glycol: The 2.1 Angstrom Resolution Crystal Structure
Overview
Human hemoglobin binds oxygen cooperatively and functions as a tetramer, composed of two identical alphabeta heterodimers. While human hemoglobin, is the best characterized allosteric protein, the quaternary R (oxygenated, or liganded) to T (deoxygenated) structural transition remains, controversial. The R2 state has been postulated to represent either an, intermediate or final quaternary state elicited by ligand binding., However, the biological relevance of the R2 state has been questioned as, it has not been observed crystallographically under physiological, conditions. The high-resolution R2 quaternary structures of human COHbC, (betaE6K) and COHbS (betaE6V) are reported at neutral pH and low ionic, strength using PEG 4000 as a precipitant. Crystals of COHbC, COHbS and, their mixtures are isomorphous, indicating that they share the same, tertiary and quaternary structures. In contrast, oxyHbA or COHbA did not, yield crystals at neutral pH under similar conditions. Solubility studies, and modeling suggest that at neutral pH and low ionic strength the beta6, mutant hemoglobins crystallize (betaK6 > betaV6) as a result of more, favorable lattice contacts.
About this Structure
1M9P is a Protein complex structure of sequences from Homo sapiens with HEM and CMO as ligands. Full crystallographic information is available from OCA.
Reference
COHbC and COHbS crystallize in the R2 quaternary state at neutral pH in the presence of PEG 4000., Patskovska LN, Patskovsky YV, Almo SC, Hirsch RE, Acta Crystallogr D Biol Crystallogr. 2005 May;61(Pt 5):566-73. Epub 2005, Apr 20. PMID:15858266
Page seeded by OCA on Thu Nov 8 13:13:22 2007
