Haemoglobin Flashcards
Why does sickling occur in deoxy form and not oxy?
in oxy form, rearrangement of subunits makes EF pocket inaccessible to val6.
What residue is mutated in sickle cell anaemia?
Glu6 in beta chains mutated to Valine
Hydrophobic valine can fit into pocket at EF corner of beta chain in another Hb molecule.
What is the hill coefficient?
Steepness at point at which protein half saturated with ligand.
Which residues are conserved and important for function in alpha and beta chains?
How do Beta chains differ?
His F8 (directly coordinates iron in haem).
His E7 (stabilises O2- bound form and destabilises CO bound form).
D chain is slightly longer!
outline the role of haem in haemoglobin.
incorporated into protein during synthesis.
Non-covalently bound but hydrophobic residues in protein interior protect oxidation of Fe2+ to Fe3+.
What does a sigmoid all curve allow?
Full saturation in lungs and maximal release at capillaries.
