1M9P

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

Summary for 1M9P

• Entry DOI: 10.2210/pdb1m9p/pdb
• Related: 1BBB 1HHO 1K1K 1RVW
• Descriptor: Hemoglobin alpha chain, Hemoglobin beta chain, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• Functional Keywords: mutant human hemoglobin c(beta e6k), r2 quaternary state of human hemoglobin, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 64659.22

Authors

Patskovska, L.N.,Patskovsky, Y.V.,Almo, S.C.,Hirsch, R.E. (deposition date: 2002-07-29, release date: 2003-08-12, Last modification date: 2024-02-14)

Primary citation

Patskovska, L.N.,Patskovsky, Y.V.,Almo, S.C.,Hirsch, R.E.
COHbC and COHbS crystallize in the R2 quaternary state at neutral pH in the presence of PEG 4000.
Acta Crystallogr.,Sect.D, 61:566-573, 2005

PubMed Abstract: 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.

PubMed: 15858266
DOI: 10.1107/S0907444905004622

Experimental method

X-RAY DIFFRACTION (2.1 Å)