The Buffer Concept Go back

The reversible, weak binding molecular interactions (in solution) between a given molecule and another molecule or an ion, are effectively described by the same concepts used to describe pH buffers involving weak acids or weak bases. Thus, the quantitative and graphical aspects of simple and complex pH buffers, such as acetic acid - a monoprotic buffer - can be reformulated to describe other biomolecular interactions.
pH buffers act like H+ ion "sponges" that bind ("soak up") or release ("squeeze out") protons.	Structure of hemoglobin and its function in binding and releasing oxygen.
Click the button on the left to "squeeze out" (release) or "absorb" (bind) protons.	Roll the mouse over these 2 images to switch between oxyHb and deoxyHbA in binding or releasing oxygen.
	Oxygen binding by hemoglobin is gauged by the saturation (Ya) or dissociation (Yd) fraction.
The binding of oxygen to Hb and its release are accompanied by noticeable conformational changes in the structure of Hb.  As Hb is transported in red blood cells from the lungs (in arterial blood) to venous blood) in the capillaries, it continuously oscillates between two (and probably more) conformational extremes:  one conformer, deoxyHb, has relatively low affinity for oxygen and the other conformer, oxyHb, has a hundred-fold higher affinity for oxygen.  In effect, Hb is like a continuously working "oxygen sponge."

©	Duane W. Sears Revised: April 3, 2019