biochem 005 kinetics and regulation part 1 (michealis-menten equation competitive inhibitor non-co
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the rate of the formation of any enzyme-substrate complex will depend on what?
it will depend on the concentration of the substrate
what is competitive inhibition?
competitive inhibitors prevent the substrate from binding active site
what is a non-competitive inhibition?
a non-competitive inhibitor binds any site on the enzyme other than the active site
what is feedback inhibition?
final product of an enzyme cascade inhibits first enzyme in the enzyme cascade
most allosteric enzymes exist in two different quaternary forms. What are these two forms called?
t and r state
which is more stable t state or r state?
the t state of an allosteric enzyme is more stable than the r state
what are the four ways in which an enzyme lower the Ea?
- 1. it will correctly orient the substrate
- 2. It will provide a favorable pH, temp., ion concentration, etc.
- 3. it strains the substrate's bonds
- 4. it covalently bonds the substrate
what is uncompetitive inhibition?
an uncompetitive inhibitor binds to the enzyme-substrate complex, preventing the product from forming
what occurs to the enzyme kinetics during competitive inhibition?
the km is increased, but the Vmax stays the same (though it takes longer to get to it)
what occurs to the enzyme kinetics during noncompetitive inhibition?
the km remains the same and Vmax is lowered
what are allosteric enzymes?
they are enzymesthat are regulated by molecules that bind to places other than their active site
what shape is the allosteric enzyme curve?
is hemoglobin an allosteric enzyme?
why is the allosteric enzyme curve sigmoidal?
If one mixes a low concentration of substrate with allosteric enzyme, little product will be produced because the allosteric enzyme is predominantly in the t (lower affinity) state
When the concentration of the substrate is increased, eventually enough substrate will be present so that, when a relaxed form of the enzyme spontaneously appears, the substrate will bind to it. Once one substrate binds to one subunit of the allosteric enzyme, all of the other subunits of the all will have a higher affinity for the substrate, a phenomenon known as cooperativity, which accounts for the sigmoidal allosteric curve
oxygen binds hemoglobin/myoglobin because of ___ ____
which has a higher affinity for oxygen? myoglobin or hemoglobin?
what are the two states in which hemoglobin can be in?
oxy (r state) and deoxy (t state)
true or false? myoglobin is not a cooperative enzyme
what does 2,3-bisphosphoglycerate do?
it stabilizes the t state in hemoglobin. That is, it makes oxygen disassociate from hemoglobin
what is the Bohr shift?
in the presence of less oxygen, hemoglobin is more conducive to oxygen. Conversely, when there is a lower pH in the blood, hemoglobin releases oxygen in order to facilitate the removal of CO2
what is unique about fetal hemoglobin?
one of the alpha chains in the fetal hemoglobin is made into a gamma chain to lower the affinity of hemoglobin to 2,3-BPG, making its affinity for oxygen increase
what happens to the kinetics of an enzyme during uncompetitive inhibition?
Vmax is decreased and KM is decreased
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