I read on Wikipedia that 2,3 BPG binds with the deoxygenated state of hemoglobin and helps in stabilizing it. It was also written that it helps release remaining oxygen from the hemoglobin. How?
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1$\begingroup$ Possible duplicate of Effect of 2,3-bisphophoglycerate (2,3-BPG) on haemoglobin $\endgroup$– DavidJul 26, 2018 at 20:53
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3 Answers
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You've answered your own question. The association/dissociation of oxygen is an equilibrium reaction. If you stabilize one state, you move the equilibrium to that state. 2,3-BPG helps release oxygen from Hb exactly by binding and stabilizing deoxy-Hb.
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From more mechanistic point of view, 2,3-biphosphoglycerate contains 2 negatively charged phosphate groups, which interacts with positively charged groups of each beta-chain within deoxyhaemoglobin decreasing the oxygen affinity (see good old Stryer Biochemistry)
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If I understand your question, you want to know, HOW the 2,3-biphosphoglycerate helps release the oxygen from the heme. In addition to other factors like the blood temperature, the pH, and the ambient pCO2, it modifies the heme oxygen affinity. It binds, using salt bridges to lysine and histidine of deoxygenated heme subunits and, by this, changes the deoxygenated heme's conformation. The so modified heme conformation renders the (oxygenated) heme-oxygen bond instable. The altered heme subunit conformation cannot hold the oxygen atom anymore, which dissociates from the heme subunit and diffuses to the mitochondria, thus allowing for ATP production. This process is called "the hemoglobin oxygen affinity is being reduced" and one of the promoting factors of this process is 2,3-DPG.
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1$\begingroup$ This looks like an informative answer, but it would be made more helpful for others if it cited sources or linked materials. $\endgroup$ Aug 25, 2022 at 22:14
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$\begingroup$ Comment to M.P.'s note from Aug 25, at 22h14 $\endgroup$ Sep 2, 2022 at 22:39
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$\begingroup$ Comment to M.P.'s note from Aug 25, at 22h14. From my point of view, the 2,3-DPG does not stabilize the hemoglobin but the oxygen's affinity to hemoglobin, as is stated in the original Q and also in the first A to the original Q, This is far from being the same thing. My intention was to draw attention to this fact, which was incorrectly stated in the original Q and also in De Novo's upvoted answer. The source of my A (answer) is : en.m.wikipedia.org/wiki/2,3-Bisphosphoglyceric_acid $\endgroup$ Sep 2, 2022 at 22:57
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$\begingroup$ It's helpful to have these sources in the answer. I don't take a position on the subtleties of deoxy Hb stabilization mechanism, but if these subtleties exist, it's handy to have very clear visuals or explanatory references, e.g. slides 15-20 or so of this presentation. Wiki is also generally fine, your page looks reasonable, though I don't see any notable distinction between the answers. The important thing is to have all this stuff in the answer itself. $\endgroup$ Sep 3, 2022 at 12:31