High-resolution X-ray study of deoxyhemoglobin Rothschild 37 beta Trp----Arg: a mutation that creates an intersubunit chloride-binding site.Kavanaugh, J.S., Rogers, P.H., Case, D.A., Arnone, A.
(1992) Biochemistry 31: 4111-4121
- PubMed: 1567857
- Primary Citation of Related Structures:  1HBA
- PubMed Abstract:
- Specifically Carboxymethylated Hemoglobin as an Analogue of Carbamino Hemoglobin: Solution and X-Ray Studies of Carboxymethylated Hemoglobin and X-Ray Studies of Carbamino Hemoglobin
Fantl, W.J.,Didonato, A.,Manning, J.M.,Rogers, P.H.,Arnone, A.
(1987) J.Biol.Chem. 262: 12700
- The Crystal Structure of Human Deoxyheamoglobin at 1.74 Angstroms Resolution
Fermi, G.,Perutz, M.F.,Shaanan, B.
(1984) J.Mol.Biol. 175: 159
The mutation site in hemoglobin Rothschild (37 beta Trp----Arg) is located in the "hinge region" of the alpha 1 beta 2 interface, a region that is critical for normal hemoglobin function. The mutation results in greatly reduced cooperativity and an o ...
The mutation site in hemoglobin Rothschild (37 beta Trp----Arg) is located in the "hinge region" of the alpha 1 beta 2 interface, a region that is critical for normal hemoglobin function. The mutation results in greatly reduced cooperativity and an oxygen affinity similar to that of hemoglobin A [Gacon, G., Belkhodja, O., Wajcman, H., & Labie, D. (1977) FEBS Lett. 82, 243-246]. Crystal were grown under "low-salt" conditions [100 mM Cl- in 10 mM phosphate buffer at pH 7.0 with poly(ethylene glycol) as a precipitating agent]. The crystal structure of deoxyhemoglobin Rothschild and the isomorphous crystal structure of deoxyhemoglobin A were refined at resolutions of 2.0 and 1.9 A, respectively. The mutation-induced structural changes were partitioned into components of (1) tetramer rotation, (2) quaternary structure rearrangement, and (3) deformations of tertiary structure. The quaternary change involves a 1 degree rotation of the alpha subunit about the "switch region" of the alpha 1 beta 2 interface. The tertiary changes are confined to residues at the alpha 1 beta 2 interface, with the largest shifts (approximately 0.4 A) located across the interface from the mutation site at the alpha subunit FG corner-G helix boundary. Most surprising was the identification of a mutation-generated anion-binding site in the alpha 1 beta 2 interface. Chloride binds at this site as a counterion for Arg 37 beta. The requirement of a counterion implies that the solution properties of hemoglobin Rothschild, in particular the dimer-tetramer equilibrium, should be very dependent upon the concentration and type of anions present.
Department of Biochemistry, University of Iowa, Iowa City 52242.