Protein Function Flashcards
Which protein that we studied is a monomer?
Myoglobin
Which protein that we studied is a oligomer?
Hemoglobin
What is the major function of hemoglobin?
Binds to oxygen in the lungs and releases it in the tissues.
What is the major function of myoglobin?
Binds oxygen in muscle
What ability of proteins does the function heavily depend on?
Ability to bind to other small molecules REVERSIBLY
The ______ the affinity of Y for X the more XY we will have at any [] of X or Y.
Greater
What is Kd?
The concentration of ligand that gives 50% binding.
A small Kd =
high affinity
The structure of myoglobin is…
153 amino acids, 8 alpha helices + loops and a heme prosthetic group.
Where does heme fit perfectly in myoglobin?
Hydrophobic pocket between E and F.
Heme is…
circular and planar
Fe2+ in heme can form how many coordination bonds?
6
How is the porphyrin ring in heme held in place?
Hydrophobic interactions and coordination bond between Fe2+ and HisF8.
What is the main function of HisF8 (proximal)?
Permanently attach heme to global.
Where does oxygen bing to the heme group in myoglobin?
the 6th coordination position.
Oxygen always bonds at an angle, true of false?
True
Which His helps prevent oxidation of Fe2+?
HisE7 (distal)
Binding sites are designed precisely to optimize binding…
Specificity and affinity
Which His allows specificity for oxygen binding at the heme?
HisE7
Myoglobin has a _____ plot.
Hyperbolic
Does myoglobin have quaternary structure?
No, only tertiary.
How many subunits does hemoglobin have?
4
How many O2 can Hb bind?
4
Define conservative substitutions.
Minor effects on structure
