Flashcards in Enzymes (Ross) Deck (22)
At what values of ΔGo′ and Keq are the products favored?
ΔGo′ less than 0
Keq greater than 1
At what values of ΔGo′ and Keq are the reactants favored?
Keq less than 1
What is the equation for Gibb's free energy?
Name the four different catalytic strategies
General acid-base catalysis
Catalysis by approximation
Metal ion catalysis
What is the Michaelis-Menten equation?
What relation describes the fraction of active sites filled?
What are the assumptions of the Michaelis-Menten equation?
•Formation of ES complex
•No back reaction from product buildup i.e. k4=0
•Initial velocities used for analysis
•Steady state assumption for [ES]
•Negligible depletion of substrate i.e. [S]>[E]
Define the Michaelis constant Km
Define the turnover number and what it measures
Measure of the catalytic ability of the enzyme when the active sites are saturated
Define catalytic efficiency
What is a perfect enzyme?
One whose catalytic efficiency is limited only by the rate of diffusion of the substrate to the enzyme
What the characteristics of the Lineweaver-Burk plot?
For two-substrate kinetics, name the three types of mechanisms
Ping-pong (double replacement)
Describe the changes in Vm, Km, and Kcat/Km for competitive inhibitors
Vm stays the same
Describe the changes in Vm, Km, and Kcat/Km for noncompetitive inhibitors
Km stays the same
Describe the changes in Vm, Km, and Kcat/Km for uncompetitive inhibitors
kcat/Vm stays the same
Describe the changes in the Lineweaver-Burk plot for competitive inhibitors
Y-intercept stays the same, slope increases
Describe the changes in the Lineweaver-Burk plot for noncompetitive inhibitors
X intercept stays the same, slope increases
Describe the changes in the Lineweaver-Burk plot for uncompetitive inhibitors
Slope stays the same, line moves higher
Describe the effect of irreversible inhibitors on Michaelis-Menten parameters
Km stays the same
Name the three types of irreversible inhibitors