Lecture 13, Kinetics (Ford) Flashcards
List the 3 kinetic trends that are possible.
Linear, hyperbolic, sigmoidal
What is the equation for a linear kinetic trend?
v = k[S]
What is the equation for a hyperbolic kinetic trend?
v0 = (vmax*[S]) / (Km + [S])
What is the equation for a sigmoidal kinetic trend?
v = [S]^n / KD + [S]^n
How do you determine the reaction order based on the graph?
Linear line (k is the absolute value of the slope of the line)
Describe the linear graph for first order kinetics.
ln[S] vs. time
Describe the linear graph for second order kinetics.
1/[S] vs. time
Describe the linear graph for zero order kinetics.
[S] vs. time
What are the substrate-independent interpretations of a zero order reaction?
Unimolecular reaction and enzyme is saturated
T or F: For a reversible reaction, the substrate is being both used and created.
True.
What is the equation for a reversible reaction at equilibrium?
k1[S] = k-1[P]
For a reversible reaction, how can the association and dissociation constants be redefined?
KA = k1/k-1 KD = 1/KA
T or F: No matter what, catalysis is a first order reaction.
False. Michaelis-Menten enzymes follow first order kinetics, but not matter what, catalysis is not a first order reaction.
How can reaction rate a catalysis be simplified if we make some assumptions?
E + S ← → E * S → E + P
When reaction rate is simplified, describe the changes in concentration.
Linear
T or F: [E] cannot be measured.
True.
Moving toward a Michaelis-Menten equation and assuming that the binding of the substrate is at equilibrium, how can the equilibrium constant be defined?
KS = KD; KS = k-1/k1
Regarding reaction rate simplification, what is the steady state assumption?
[S]»_space; [E]
Regarding reaction rate simplification, describe the formation of the E*S complex.
Formation occurs at the same rate as its loss
What is the rate-determining step when simplifying the reaction rate?
k2
Since k2 is the rate-determining step, what is the rate of product formation?
v0 = kcat * [E*S]
Why can’t [E*S] be meaured?
Transient and unstable
What does it mean when vmax is reached?
Enzyme is fully saturated; [E*S] = [E]T
Describe the kcat of a good enzyme.
kcat»_space; k-1; kcat/Km ~ k1
Describe the kcat of a poor enzyme.
kcat «_space;k-1; kcat/Km ~ 1/Km
T or F: Multiple binding site enzymes can follow Michaelis-Menten kinetics, whether they are cooperative or noncooperative.
False. Multiple binding site enzymes can follow Michaelis-Menten kinetics, as long as they are noncooperative.
What is the equation for a Lineweaver-Burk plot?
1/v0 = Km/vmax * 1/[S]0 + 1/vmax
T or F: Inhibitors can be reversible or irreversible.
True.
What kind of bonds do reversible inhibitors utilize?
Noncovalent interactions
What are the types of inhibition reversible inhibitors use?
Competitive, noncompetitive, uncompetitve
Which of the reversible inhibitors are allosteric?
Noncompetitive, uncompetitive
Describe the vmax and Km of competitive inhibitors.
vmax = constant Km = variable
Describe the vmax and Km of noncompetitive inhibitors.
vmax = variable Km = constant
Describe the vmax and Km of uncompetitive inhibitors.
vmax = variable Km = variable
What does the graph for a competitive inhibitor look like?
Chopsticks
What does the graph for a noncompetitive inhibitor look like?
V
What does the graph for a uncompetitive inhibitor look like?
Railroad tracks
What do irreversible inhibitors do?
Inactivate enzymes
What do group-specific irreversible inhibitors target?
Specific amino acid (low specificity)
What do substrate analog irreversible inhibitors target?
Substrate mimic, modifies enzyme (high specificity)
What do suicide inhibitor irreversible inhibitors target?
Substrate mimic, unable to form products (very high specificity)
