The Hr Effect : The Bohr Effect

960 Words4 Pages
Intimate structure-function relationship of the Hb subunits allows cooperative binding of a gas molecule in a reversible manner. Hydrophobic pocket in Hb subunit allows tight binding of heme molecule as well as reversible binding of O2 so that Hb can shift from oxygenated ‘tense (T)’ form (oxyhemoglobin) to deoxygenated ‘relaxed (R)’ form (deoxyhemoglobin) (4,10). When oxygen binds to deoxyhemoglobin, a conformational change occurs and changes an ionization state of amino acid which is associated with oxygen binding affinity (9). These changes result in either release or absorption of protons and this is what is so-called Bohr effect. Bohr effect is a significant factor that determines how efficiently Hb molecules are disposed to the body tissues (9,10). Experimental data collected over several decades suggest that there are two types of Bohr effect: (i) acid Bohr effect (pH≈6), proton absorption by Hb is called negative contribution where oxygen affinity of Hb reduces (ii) alkaline Bohr effect (pH > 6), proton ejection from Hb is also known as positive contribution to Bohr effect where the affinity increases (5,8,10). The Bohr effect assists Hb by facilitating the release of oxygen molecule when oxygen supply is needed for instance, in exercising muscle where O2 level and pH is lower. Understanding of acid Bohr effect can be used in treating of the metabolically challenged region of the body. Acidifying tissue will result in hypoxia and lower O2 affinity, thus O2 will be
Open Document