Kaplan FL 1 Flashcards BIOCHEM 2
Find the equilibrium constant expression
pure solids and pure liquids are NOT part of equilibrium expression– only nitric oxide and water vapor
what do competitive inhibitors do?
they INCREASE Km
Vmax satys the same
How does competitive inhibitor look on Lineweaver Burke plot?
Lineweaver Burk
x intercept closer to 0 (bigger Km)
same y intercept (same Vmax)
How does competitive inhibitor look on Michealis Menton plot?
V max is the same
Km increases which means more substrate is needed to reach Vmax
Km is 1/2 Vmax
What does Lineweaver Burke plot look like
What does the Michealis Menten plot look like?
cooperative enzymes
Certain enzymes do not show the normal hyperbola when graphed on a Michaelis–Menten plot (v vs. [S]), but rather show sigmoidal (S-shaped) kinetics owing to cooperativity among substrate binding sites
Subunits and enzymes may exist in one of two states: a low-affinity tense state (T) or a high-affinity relaxed state (R). Binding of the substrate encourages the transition of other subunits from the T state to the R state, which increases the likelihood of substrate binding by these other subunits. Conversely, loss of substrate can encourage the transition from the R state to the T state, and promote dissociation of substrate from the remaining subunits.,
example of cooperative binding enzyme in glycolysis
Enzymes showing cooperative kinetics are often regulatory enzymes in pathways, like phosphofructokinase-1 in glycolysis. Cooperative enzymes are also subject to activation and inhibition, both competitively and through allosteric sites.
The cooperative binding of hemoglobin, which acts as a transport protein rather than an enzyme, results in a characteristic sigmoidal binding curve that is an MCAT favorite.
What is Hills coefficient?
number for the cooperativity of an enzyme
if >1, positive cooperative binding such that after one ligand is bound the affinity of the enzyme for further ligand(s) increases.
If < 1, negatively cooperative binding is occurring, such that after one ligand is bound the affinity of the enzyme for further ligand(s) decreases.
If = 1, the enzyme does not exhibit cooperative binding.
