Myoglobin And Haemoglobin Flashcards
Why is myoglobin a tertiary structure
Only 1 polypeptide chain
How many heme groups does myoglobin have and what does it consist of
1 heme group with FE2+ and protoporphyrin
Is myoglobin alpha or beta
Alpha
Why is haemoglobin called a TETRAMER?
It has 4 subunits 2 Alpha 2 beta
What’s the main difference in jobs for haemoglobin and myoglobin?
Myoglobin binds to oxygen at muscles
Haem binds to oxygen in lungs
Myoglobin acts as a store for tissues
Haemoglobin associates and dissociates
Haemoglobin binds to oxygen cooperatively, what does this mean
One binding of 02 allows for binding in other subunits
How does the binding of one oxygen to haemoglobin chain the shape
Triggers a 15• turn of all 4 chains. This allows for the oxygen binding site to be free of strain
What are the states called when oxygen site is either strained and becomes unstrained after binding?
T state - tense state (deoxyhaemoglobin)
R state- resting state = oxygen binding (Oxyhaemoglobin)
Why do large mammals like whales need myoglobin
Oxygen store which builds for when they dive
Along with FE2+, what else is in a heme?
Protoporphyrin
FE2 has 2 binding sites called coordinating sites (5 + 6) what are they bound to
5 = histidine
6= oxygen
Oxygen when bound means FE moveS to inside the porphyrin, it carries histidine. What’s the important of that
The a helix strand carboxyl changes in site which allows communication between the 4 subunits - T - R state transition
Explain the effect of hydrogen and co2 produced by cells on dissociation of oxygen (Bohr effect)
They bind to sites on haemoglobin
It lowers the ph of the blood
Low ph allows for dissociation as histidine will form saltbridges in low ph (protonates as it is a base)
This returns it to T state
Co2 reaction with water can also cause dissociation. How
Forms carbonic acid which lowers ph
In the bicarbonate ion state this causes histidine saltbridges to form again (it becomes protonated)
