Torillian on 23 February 2008
The changing shape of Hemoglobin allows it to bind each successive Oxygen pair more efficiently than the last. As each Heme group binds to an Oxygen it puts a strain on the Oxygen-less Heme groups in the other subunits of Hemoglobin and will eventually cause a conformational change in the other subunits that makes Oxygen bind more efficiently. This switch from a Tense state to a relaxed state and back again is the reason Oxygen binds to Hemoglobin with a sigmoid pattern instead of a hyperbolic curve.
As Epsi said....this is a theory that is widely supported by experimental data and the scientific community as a whole.
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