Spontaneous Quaternary and Tertiary T-R Transitions of Human Hemoglobin in Molecular Dynamics Simulation
(A) X-ray structures of Hb in the R state (green) and in the T state (red). The T-R quaternary transition is mainly characterized by a rotation of the α1/β1 dimer (colored) with respect to the α2/β2 dimer (gray). To visualize the rotation, the α2/β2 dimers of the R and T structure were superimposed on each other. (B) A typical dodecahedral simulation box of Hb. The Hb tetramer is shown in cartoon representation, sodium and chloride ions as red and blue spheres, respectively, and water is depicted as transparent sticks. The molecular representations were made with Pymol .