Deoxyhemoglobin quaternary structure

Figure 4.4 Quaternary structure of deoxyhemoglobin tetramer visualized using Wavefunc-tion, Inc. Spartan 02 for Windows from PDB data deposited as 4HHB. See text for visualization details. Printed with permission of Wavefunction, Inc., Irvine, CA. (See color plate.)...

Figure 7.2 Quaternary structure of deoxyhemoglobin tetramer (PDB 4HHB). Visualized using The PyMOL Molecular Graphics System and ChemDraw Ultra, version 10.0. (Printed with permission of Delano Scientific, LLC and CambridgeSoft Corporation.)... 

Oxyhemoglobin has a different quaternary structure from deoxyhemoglobin. As 02 binds to the Fe2+ it distorts the heme group and moves the proximal histidine. This in turn moves helix F and alters the interactions between the four subunits. 

Finally, there is another piece of experimental evidence supporting the suggestion that the ferrous hfs proton resonances are sensitive to the quaternary structural state of hemoglobin. In 1971, we investigated the ferrous hfs proton resonances of four mutant deoxyhemoglobins, Hb Chesapeake [a92(FG4)Arg —> Leu], Hb J Capetown [a92(FG4)Arg - Gin], Hb Yakima [ 399(Gl)Asp - His], and Hb Kempsey [099(Gl)Asp —> Asn], which have amino acid substitutions in the ai(J2 subunit interface (Davis etal., 1971) The locations of these mutant Hbs are shown in Fig. 11. Figure 39 shows the effects of these... 

Figure 7.5 Quaternary structure of deoxyhemoglobin. Hemoglobin, which is composed of two a chains and two p chains, functions as a pair of a(3 dimers. (A) A ribbon diagram. (B) A space-tng model. [Drawn from lA3N.pdb.]...

Figure 7.19 Chemical basis of the Bohr effect. In deoxyhemoglobin, three amino acid residues form two salt bridges that stabilize the T quaternary structure. The formation of one of the salt bridges depends on the presence of an added proton on histidine (3146. The proximity of the negative charge on aspartate [394 in deoxyhemoglobin favors protonation of this histidine. Notice that the salt bridge between histidine 3146 and aspartate 3 4 is stabilized by a hydrogen bond (green dashed line).

ZERBI asked whether there is any hope of detecting conformational changes in proteins by using NMR. BOVEY felt that the answer to this was yes and cited the example of oxy- and deoxyhemoglobin, where there were correlations between the changes in the NMR spectra and the quaternary structure of the protein. 

The quaternary structure adopted by the hybrids is the T form, where the metal-metal distance is 25 A the porphyrin planes are approximately parallel and the edge-edge distance is —20 A (Fig. 21). In the deoxyhemoglobin structure, the subunits of closest approach are aiP2- Since a,p ... 

It has been recently argued (58) that as deoxyhemoglobin (which can bind red cell folate electrostatically) picks up oxygen and switches quaternary structure, any bound folate can become physically trapped. Venous blood taken... 

Roche, C.J., Dantsker, D., Samuni, U., and Friedman, J.M. (2006) Nitrite reductase activity of sol-gel-encapsulated deoxyhemoglobin influence of quaternary and tertiary structure./. Biol. Chem.,... 

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