MCBG S4 Enzyme Activity And Inhibition Flashcards
What is the function of an enzyme?
They increase the rate of a reaction by lowering the activation energy, this is accomplished because they facilitate the formation of a transition state.
State and briefly describe the 2 theories for enzyme action.
The lock and key hypothesis - active site is exactly complementary to the substrate.
Induced fit hypothesis - active site conforms to a complementary shape after the substrate binds.
How do substrates bind to their active sites?
H bonds
Hydrophilic and hydrophobic interactions.
What is Vmax?
Maximal rate when all enzyme active sites are saturated with substrate.
What is Km?
Substrate concentration at which half Vmax is achieved.
What is Km a measure of?
The affinity of an enzyme
Lower Km, higher affinity.
Define 1 unit.
Amount of enzyme that converts 1umol of product per minute under standard conditions.
If you double amount of enzyme you double the standardised rate, true or false?
False, this is only true for normal rate.
What is an alternative graph we can plot to show enzyme kinetics other than rate-concentration?
Lineweaver burk plot.
Reciprocal plot.
1/V vs 1/[S]
What does the gradient of a lineweaver burk plot represent?
Km/Vmax
Ratio of Km to Vmax
What does the Y intercept of a lineweaver burk plot represent?
1/Vmax
What does the X intercept of a line weaver burk plot represent?
-1/Km
What affect do reversible inhibitors have on Km and Vmax?
Increase Km and no effect on Vmax.
What affect fo irreversible inhibitors have on Km and Vmax?
Reduce Vmax and no effect on Km.
Adding more substrate will overcome the effects of a non-competitive inhibitor, true or false?
False.
