1. Hemoglobin Tetramer [Hb(O 2 )] [Hb]P O 2 K 2 = [Hb(O 2 )] [Hb]P O 2 K 3 = [Hb(O 2 )] [Hb]P O 2 K 4 = [Hb(O 2 )] [Hb]P O 2 K 1 = = 4.88 = 15.4 = 6.49 = 1750 Whole blood can carry as much as 0.01 moles of O 2. Plasma can carry only 0.0001 moles of O 2 Hb (aq) + O 2(g) Hb(O 2 ) (aq) Hb(O 2 ) (aq) + O 2(g) Hb(O 2 ) 2(aq) Hb(O 2 ) 2(aq) + O 2(g) Hb(O 2 ) 3(aq) Hb(O 2 ) 3(aq) + O 2(g) Hb(O 2 ) 4(aq)

4. Myoglobin Tetramer [Mb(O 2 )] [Mb]P O 2 K = = 271 Mb (aq) + O 2(g) Mb(O 2 ) (aq) Change the partial pressure of O 2 will shift the equilibrium. Increasing P O 2 will shift the equilibrium to the right, decreasing P O 2 will shift the equilibria to the left.

5. Myoglobin –Higher affinity for O 2 (low P O 2 ) –Hyperbolic binding –O 2 :Mb 1:1 –Binds O 2 in tissues Hemoglobin –Lower affinity for O 2 (High P O 2 ) –sigmoidal binding –O 2 :Hb 4:1 –Binds O 2 in lungs, releases in tissues At a P O 2 of 0.13 atm both hemoglobin and myoglobin are 95% saturated. With a P O 2 of 0.040 atm hemoglobin is only 55% saturated whereas myoglobin is above 90%. Thus, as P O 2 decreases in the capillaries hemoglobin releases almost half Of the O 2 which O 2 poor myoglobin can pick up.