Haemoglobin Flashcards
What is a haem group ?
protoporphyrin ring with a Fe atom attached to the 4 N of the ring
What is Fe attached to either side of ring?
oxygen and proximal histidine
What happens when oxygen binds myoglobin?
Fe sits just underneath ring oxygen binds fe moves into plan of ring proximal histidine moves small conformational change in the protein
Why is myoglobin binding curve hyperbolic and not sigmoidal?
only single protein chain therefore cannot show co-operativity
What is co operativity?
Hb affinity for oxygen not constant hence hyperbolic curve
low affinity T state and high affinity R state
as oxygen binds the conformational changes promotes and stabilises the R state increase Hb affinity for oxygen
What is 2,3 BPG?
What happens at high altitude?
2,3- bisphosphoglycerate
binds centre of tetramer and decrease Hb affinity for oxygen
at high altitude increases to improve delivery of oxygen to tissues as less oxygen picked up at lungs and difference in partial pressure between blood and tissues reduced
What is the Bohr effect?
Co2 and h shift curve to the right, reduce Hb affinity for oxygen
means increase delivery of oxygen to tissues that are metabolically active
What is the difference between fetal and adult Hb ?
fetal has increased affinity for oxygen to allow exchange of oxygen form mother to baby
What happens in CO poisoning?
CO bind Hb 250 x more strongly than o2
prevents oxygen binding
How can you treat CO poisoning?
blood transfusion
hyperbaric chamber to super saturate with oxygen to try and compete with CO
What happens in sickle cell anaemia?
glutamate to valine creates hydrophobic pocket
therefore deoxy HbS polymerises
lyse of rbcs and blockage of microvascualture commone
What is thalassemia?
genetic disorders that result in imbalance between number of alpha and beta globin chains
What happens in beta thalassemia?
absence/ reduce beta globin
alpha cannot form tetramer resulting in precipitate
block bv
symptoms after birth
What happens in alpha thalassemia?
absence/ reduce alpha globin
multiple copies of alpha chain so varying severities
beta globin forms tetramer that has increased affinity for oxygen
onset before birth
