Which of the following is not true about buffering action of haemoglobin (Hb)?
Protein buffers in blood include haemoglobin (150g/l) and plasma proteins (70g/l). Buffering is by the imidazole group of the histidine residues which has a pKa of about 6.8. This is suitable for effective buffering at physiological pH. Haemoglobin is quantitatively about 6 times more impoant than the plasma proteins as it is present in about twice the concentration and contains about three times the number of histidine residues per molecule.
Hb is technically intracellular buffer
Hb is functionally a plasma buffer
Hb's buffering action is due to its histidine content
Oxygenated Hb is a strong base
Metabolism of nucleic acids