Biology 3601 Fall 2013

partial pressure of oxygen pO2

is proportional concentration

P50 = 0.26 kPa

Hemoglobin: for O2 transport

Myoglobin and Hemoglobin

Hemoglobin Function

http://classconnection.s3.amazonaws.com/38/flashcards/1293038/png/oxygen_transport1336075699361.png

Hemoglobin Fractional Saturation

Implications

The binding of one oxygen to hemoglobin makes the binding of additional oxygen molecules to hemoglobin ‘easier’. The KD for the first ligand is higher than the KD for subsequent ligands.

The dissociation of one oxygen from hemoglobin makes the dissociation of the remaining oxygen molecules from hemoglobin ‘easier’.

This is a hallmark of a phenomena known as cooperativity. In cooperativity, the binding of one ligand to a protein affects the binding of subsequent ligands to that molecule.

Cooperativity minimally requires a protein to have more than one ligand binding site.