Question 3
In humans, the urge to exhale results from the highconcentration of CO2 in the blood. Divers often hyperventilate(rapid breathing for several minutes) prior to making a dive in thebelief that this will increase the O2 content in their blood. Useyour knowledge of haemoglobin function to evaluate whether thispractice is useful.
Question 4
Glutathione is a tripeptide, ECG. It contains an unusual peptidelinkage between the amine group of cysteine and the carboxyl groupof the glutamate side chain. It is an antioxidant and helps protectcells from reactive oxygen species such as free radicals andperoxides.
a) Draw the structure of the tripeptide and estimate itsisoelectric point (pI).
b) The Cys moiety can be readily oxidized to form disulphidebonds. It is crucial that this tripeptide is maintained in thereduced form else it will lose its ability to transport oxygeneffectively. Why do you think this is so?
Question 5
One molecule of 2,3-bisphosphoglycerate (BPG) binds to onemolecule of haemoglobin (Hb) in a central cavity of the haemoglobinmolecule. Is the interaction between BPG and Hb stronger or weakerthan it would be if BPG were bound to the surface of the proteininstead? Explain your answer.
