Haemoglobin and Myoglobin Flashcards
What are the key features of the structure of haemoglobin?
2 polypetide chains, alpha (141 amino acids) and beta (146 amino acids) in a tetramer of two alpha chains and two beta chains. Confirmation of each polypeptide chain is similar to myoglobin .
What are the two oxygen binding states of haemoglobin?
T state=low affiniity
R state= high affinity
How does binding of oxygen increase the affinity of a globin molecule for oxygen?
Fe in deoxyhaemoglobin is slightly below the plane of the ring, binding of a oxygen helps to pull the fe into the plane of the ring and therefore increases the binding capabilities for oxygen.
What kind of binding curve does haemoglobin display?
Sigmodial
What kind of binding curve does myoglobin display?
Hyperbolic
How does 2,3 bisphosphoglycerate affect oxygen binding and how can this be beneficial?
2,3 bisphosphoglycerate reduces the affinity of haemoglobin to oxygen. This is useful as it is a by-product of glycolysis so oxygen can be directed to metabolically active tissues and can also be used to increase release of oxygen from haemoglobin at high altitudes.
What is the effect of CO2 and h+ on tissues commonly known as and what is the benefit of this?
This is called the Bohr affect, and this is a decrease in the affintiy of heamoglobin for oxygen in the presence of these substances. It means that more oxygen can be delivered for metabollically active tissues.
What is the mutation present in sickle cell anaemia and how des this affect protein structure?
This is a mutation from glutamate to valine in the beta-globin chain, which forms a sticky hydrophobic pocket that allows oxygenated hameoglobin to polymerise, making cells more prone to lyse and a lower flexibility of blood molecules.
What is a thalassemnia?
A group of genetic disorders resulting from a imbalance between the alpha and beta globin chains?
What is the effect of b-thalassemia?
There is decreased or absent b-chain production, resulting in a chains being unable to form stable tetramers. This is a condition which typically onsets after birth.
What is the effect of a-thalassemia?
There are varying levels of severity due to the presence of multiple genes from the alpha chains, however, beta chains can form stable tetramers with increased affinity for oxygen.
What are the key features of myoglobin structure
75% a helical, 153 amino acids, compact, histidine 93 in 8th alpha helix is covalently linked to fe.
