Flashcards in Protein Function Deck (35):
Which protein that we studied is a monomer?
Which protein that we studied is a oligomer?
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.
What is Kd?
The concentration of ligand that gives 50% binding.
A small Kd =
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.
circular and planar
Fe2+ in heme can form how many coordination bonds?
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?
Which His helps prevent oxidation of Fe2+?
Binding sites are designed precisely to optimize binding...
Specificity and affinity
Which His allows specificity for oxygen binding at the heme?
Myoglobin has a _____ plot.
Does myoglobin have quaternary structure?
No, only tertiary.
How many subunits does hemoglobin have?
How many O2 can Hb bind?
Define conservative substitutions.
Minor effects on structure
Define critical substitutions.
Can change structure and therefore function
Hyperbolic curve is indicative of...
Sigmoidal curve is indicative of...
cooperative binding affinity
Hemoglobin has a _________ plot.
Sigmoidal oxygen binding curve means...
Cooperative process, necessary for efficient O2 delivery, reflects a change in binding affinity
How does Hb change its affinity for oxygen?
What are the two states of Hb?
Tense (low affinity, more salt bridges) and relaxed (high affinity, less salt bridges)
What is allostery?
The binding of a ligand at one site on a protein affects the binding of ligands at other sites.
What is homoallosteric?
Binding of the effector affects further binding of the SAME compound
What is heterosteric?
Binding of the effect affects further binding of a DIFFERENT compound