BIOCHEMISTRY 3521

Study Guide #4 -- Enzymes and Kinetics

Material Provided in part by R. Morse (ILSTU, Chem 242)

Some Material is form Biochemistry 460 at Arizona

1- Define: catalysis, activation energy, active site, enzyme-substrate complex. What general properties do enzymes have as catalysts which are especially important for their biological roles?

2- Explain the structural basis of substrate specificity in terms of the "lock and key" and "induced fit" models.

3- Define the Michaelis-Menten equation in words. What two assumptions does the Michaelis-Menten equation make to allow it to be a useful model of real world enzyme kinetics? What is the Michaelis-Menten mechanism for an enzyme-catalyzed reaction?

Michaelis-Menten equation

Define the terms in this equation (i.e. V_max, K_M, k_cat)

Draw graphs which illustrate the meaning of these terms and how values for them may be obtained experimentally.

4. What is the rate-limiting step in an enzymatic reaction? How would you experimentally determine what that rate was? (Assume you can measure the rate of an enzyme by some method. What conditions of enzyme and substrate concentrations would be appropriate to make this determination?).

4- Define competitive and non-competitive inhibition. Show graphically how these may be distinguished from each other. What are the effects on Km and Vmax and discuss the place on the enzyme where the inhibitor interacts.

5- Give some specific examples of reversible and irreversible enzyme inhibition.

see the Study Questions & Answers on Bioenergetics and Kinetics and Enzyme Biochemistry at MIT