Hemoglobin

Front 1

What mutation causes sickle cell anemia?

Back 1

Changing a glutamic acid to a valine, which is caused by a change from the GAG codon to the GUG codon

Front 2

What specific affect on Hg structure does changing a glutamine to a valine have?

Back 2

When the Hg molecule is oxygenated the structure is not affected, but when oxygen is removed the mutation allows Val (1st Hg molecule) to bind to hydrophobic pocket of 2nd Hg molecule

Front 3

Where is myoglobin found? what cofactor does it require for O2 binding?

Back 3

Primarily in muscle; requires heme cofactor for O2 binding

Front 4

What ligands bind to the center of the protein? where do most ligands bind?

Back 4

Steroid hormones bind to the center of the protein, most ligands bind to specific sites on the surface of the protein (usually in a cleft)

Front 5

What IMFs determine the binding of ligands to a protein?

Back 5

1. Coulombic (ion/ion, H-bonding, dipole/dipole)
2. Dispersion (Van der Waals)
3. Hydrophobic effect

Front 6

What is the protein conformation when a protein does not have a ligand bound? what is the conformation of a protein that is produced upon ligand binding? which state is more stable in the absence of a ligand? what state has a higher ligand affinity?

Back 6

Unbound: The "T" or terse state <+ more stable
Bound: "R" or relaxed state <+ higher affinity

Front 7

What is allosterism? what does allosterism produce?

Back 7

The effect on binding affinity that one ligand has on another; allosterism produces cooperative binding of ligands

Front 8

What is the sequential model of Hg binding? what does this model assume?

Back 8

Assumes that ligand binding causes the protein conformation to change in order to better fit the ligand

Induced conformational changes effect other ligand binding sites on protein allowing for both negative and positive cooperitivity

Front 9

What does the symmetry model assume? what does this model account for?

Back 9

Assumes that the Hg "T" and "R" states are in equilibrium and that the T state is more stable and the R state has higher affinity. Only accounts for positive cooperativity

Front 10

Which way does increased PCO2 shift the Hg binding curve?

Back 10

To the right

Front 11

What affect does decreased pH/increased [H+] have on the Hg-O2 binding curve?

Back 11

Shifts it to the right

Front 12

What effect does increased [DPG] have on the Hg-O2 curve?

Back 12

Shifts it to the right or causes decreased affinity of Hg for O2

Front 13

What form of Hg does 2,3DPG bind to preferentially?

Back 13

The deoxyHb form

Front 14

What converts insoluble CO2 into soluble bicarbonate?

Back 14

Carbonic anhydrase