Hemoglobin Flashcards
What are the Kd of oxygen and carbon monoxide in heme, Mb and in the atmosphere
What kind of hybridisation does the carbon atom undergo in carbon monoxide
Sp hybridisation
Draw the molecular orbital diagram for carbon monoxide
What is the bond order of carbon monoxide
3
Carbon is partially negative, oxygen is partially positive
This allows carbon monoxide to bind to iron as a ligand
What is the proximal histidine
It is bound to iron in heme
It is an axial ligand
What is the distal ligand in myoglobin
It is the histidine which isn’t a ligand (it isn’t bound to iron) and isn’t part of heme group but is present in myoglobin
Why does carbon monoxide bind to the iron in heme tipped
The distal histidine causes the carbon monoxide to tip when binding to iron as it is in the way
This is why carbon monoxide has a lower affinity to myoglobin
What are the different arrangements of d orbitals for iron
Show the distribution of electrons in atomic orbitals in ferric iron
Show the distribution of electrons in ferrous iron
Which of the arrangements of d orbitals in iron are most energetically favourable and why
Irons own electrons aren’t pointing towards the ligands
So the electrons from the ligands aren’t being repelled by irons electrons
Therefore this is a low energy conformation
Which of irons arrangement of d orbitals are energetically unfavourable and why
Irons electrons are pointing towards equatorial ligands for x squared and towards the axial ligands for a squared which would repel the ligands electrons
Energy would be needed to overcome repulsion
Show the filling of electrons in the 3d orbital of Fe2+
Show the filling of electrons in the 3d orbital of Fe2+ in heme
Show the filling of electrons in the 3d orbital of Fe2+ in myoglobin and what is it called
Show the filling of electrons in the 3d orbital of Fe2+ in myoglobin when oxygen is bound for each type of d orbital arrangement for iron
How is iron orientation for ‘high spin’
Iron is below the plane of the equitorial ligands so wont line up its electrons directly with the electrons of nitrogen
What is the protein conformation change that occurs when oxyge binds to iron in heme
Iron moves when oxygen is bound: it lines up with the equitorial nitrogen atoms (lines up with the plane)
Proximal histidine also moves with the iron
Therefore it pulls the helices that histidine is attached to with it which changes the shape of the protein
What is cooperatively
One subunit in a protein changes which causes a change in other subunit
What is the oligomeric structure of hemoglobin (how is it represented)
What is allosteric change
Change in shape (change in conformation) due to rotations around single bonds
How does oxygenation of heme change the structure of hemoglobin
