Bohr Effect

Bohr Effect

Although haemoglobin (Hb) is about as good an O₂ binder as myoglobin (Mb) at high O₂ pressure, it is much poorer at low pressures prevailing in muscle, hence passes its oxygen on to the Mb as required. Moreover, the need for O₂ is greatest in tissues that have already consumed oxygen and simultaneously produced CO₂. CO₂ lower the pH, thus causing the Hb to release even more oxygen to Mb. The pH dependence shown by Hb is called Bohr effect, the net result of which is to increase the release of oxygen at low pH values (high CO₂ concentrations in the tissues).
The progressive increase of O₂ binding constant in Hb are due to interactions between subunits; Mb behaves more simply because it consists of only one unit. Each of two is essential in the complete oxygen transport process. Bohr effect causes a shift in the oxygen dissociation curve to the right and is primarily responsible for the release of O₂ from the oxyhemoglobin to the tissue because of increased pCO₂ & decreased pH in the actively metabolizing cells.

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