Hemoglobin and Oxygen Exchange Physiological
Conformational Changes Accompany Oxygen Binding or Release
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  • Move the mouse pointer over the image to switch between the oxyHbA and deoxyHbA conformations of adult hemoglobin A their respective oxygen saturation levels in arterial (red) or venous (blue) blood.
  • Oxygen binding by Hb and its release are accompanied by noticeable conformational changes in the structure of Hb. 
  • As Hb is transported in red blood cells between the lungs and the capillaries, continuously oscillates between two (and probably more) conformational extremes.
  • In the "deoxyHb" conformation, which predominates in venous blood, hemoglobin's oxygen affinity is relatively low.
  •  In the "oxyHb" conformation, which predominates in arterial blood, hemoglobin's oxygen affinity is relatively high.
  • In effect, Hb is like an "oxygen sponge" when it oscillates between these conformation extremes.
Roll mouse over theimage below to switch between deoxyHb & oxyHb structure and function.
  • As illustrated by the chart, the amount of oxygen bound to
  • Hb, i.e., the saturation fraction, Ya, is measured a function of the pressure of oxygen gas in the immediate environment, pO2.
  • In arterial blood leaving the lungs, Hb has up to four oxygen molecules bound being nearly 100% saturated in this environment.  A high percentage of oxygen-saturated oxyHb molecules gives arterial blood its slightly pinkish coloration.  
  • In the capillaries or venous blood, Hb releases some its bound oxygen molecules, becoming desaturated of oxygen in this environment.  A high percentage of oxygen-depleted deoxyHb molecules gives venous blood  it is slightly bluish coloration.
 

© Duane W. Sears
Revised: October 17, 2011