1aj9
From Proteopedia
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R-STATE HUMAN CARBONMONOXYHEMOGLOBIN ALPHA-A53S
Overview
The three-dimensional structure and associated solvent of human, carboxyhemoglobin at 2.2 A resolution are compared with other R-state and, T-state human hemoglobin structures. The crystal form is isomorphous with, that of the 2.7 A structure of carboxyhemoglobin reported earlier [Baldwin, (1980). J. Mol. Biol. 136, 103-128], whose coordinates were used as a, starting model, and with the 2.2 A structure described in an earlier, report [Derewenda et al. (1990). J. Mol. Biol. 211, 515-519]. During the, course of the refinement, a natural mutation of the alpha-subunit, A53S, was discovered that forms a new crystal contact through a bridging water, molecule. The protein structure shows a significant difference between the, alpha and beta heme geometries, with Fe-C-O angles of 125 and 162 degrees, respectively. The carboxyhemoglobin is compared with other fully ligated, R-state human hemoglobins [Baldwin (1980). J. Mol. Biol. 136, 103-128;, Shaanan (1983). J. Mol. Biol. 195, 419-422] with the R2-state hemoglobin, [Silva et al. (1992). J. Biol. Chem. 267, 17248-17256] and with T-state, deoxyhemoglobin [Fronticelli et al. (1994). J. Biol. Chem. 269, 23965-23969]. The structure is similar to the earlier reported R-state, structures, but there are differences in many side-chain conformations, the associated water structure and the presence and the position of a, phosphate ion. The quaternary changes between the R-state, carboxyhemoglobin and the R2-state and T-state structures are in general, consistent with those reported in the earlier structures. The location of, 238 water molecules and a phosphate ion in the carboxyhemoglobin structure, allows the first comparison of the solvent structures of the R-state and, T-state structures. Distinctive hydration patterns for each of the, quaternary structures are observed, but a number of conserved water, molecule binding sites are found that are independent of the, conformational state of the protein.
About this Structure
1AJ9 is a Protein complex structure of sequences from Homo sapiens with PO4, HEM and CMO as ligands. Full crystallographic information is available from OCA.
Reference
Human carboxyhemoglobin at 2.2 A resolution: structure and solvent comparisons of R-state, R2-state and T-state hemoglobins., Vasquez GB, Ji X, Fronticelli C, Gilliland GL, Acta Crystallogr D Biol Crystallogr. 1998 May 1;54(Pt 3):355-66. PMID:9761903
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