Role of subunit interfaces in the allosteric mechanism of hemoglobin.
We calculate the surface area buried in subunit interfaces of human deoxyhemoglobin and of horse methemoglobin. A larger surface area is buried in deoxy- than in methemoglobin as a result of tertiary and quaternary structure changes. In both molecules the dimer-dimer interface is closepacked. This implies that hydrophobicity stabilizes the deoxystructure, the free energy spent in keeping the subunits in a low-affinity conformation being compensated by hydrophobic free energy due to the smaller surface area accessible to solvent.
D000494:Allosteric Regulation; D000818:Animals; D006441:Hemoglobin A; D006454:Hemoglobins; D006736:Horses; D006801:Humans; D008706:Methemoglobin; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D006454:Hemoglobins; D008706:Methemoglobin; D006441:Hemoglobin A