You can manipulate the structure directly by dragging with the mouse. Mouse drag down with Shift key to zoom. Try gestures on touch screen devices. Click on the links below the black box to see other useful views of the structure. Advanced users can select the Console from the function menu and directly enter JSmol commands.
The initial view shows all the hemes and the sidechains of His45 of the alpha chains. Interactions between His45s mediate the R to T transition.
See discussion of general features of hemoglobin under animation of Hemoglobin, Homo sapiens, T Conformation. The α2β2 quaternary structure of hemoglobin allows for 3 quaternary isomers. One can be identified as probable R-state because of the juxtaposition of His45s, a second can be identified as T-state because of the presence of an intact anion binding site. This third state may or may not exist in nature. If it does exist, it is likely to occur at low pH and in the absence of polyanions. It probably exists for human carbonmonoxyhemoglobin at pH 7.0 in the absence of polyanions. See post of 16 Dec 2019 re NMR data of Fan et al. (2013) Biochemistry 52, 5809 - 5820.
For further information about this protein, contact the author, Dr Don Vanselow at dvanselow@hotmail.com
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