Biochemistry Online: An Approach Based on Chemical Logic

Biochemistry Online

CHAPTER 6 - TRANSPORT AND KINETICS


C: ENZYME INHIBITION

BIOCHEMISTRY - DR. JAKUBOWSKI

06/12/2014

Learning Goals/Objectives for Chapter 6C:  After class and this reading, students will be able to

  • differentiate among competitive, uncompetitive, and mixed inhibition of enzymes by reversible, noncovalent inhibitors by writing coupled chemical equilibria equations and drawing cartoons showing molecular interactions among, E, S, and I;
  • using LeChatelier's principle and coupled chemical equilibria equations, draw double reciprocal (Lineweaver-Burk plots) and semilog plots for enzyme catalyzed reactions in the presence of different fixed concentrations of inhibitors and activators of enzyme
  • define KIS and KII for competitive, uncompetitive, and mixed inhibition from coupled chemical equilibria and double reciprocal plots;
  • differentiate between apparent and actual dissociations constants constants of an inhibitor and enzyme from double reciprocal plots and equations initial rate mathematical equations;
  • define agonist, partial agonist, antagonist, and mixed (noncompetitive antagonists) from analogy to enzymes and their inhibitors;
  • describe different ways that pH changes could affect the activity of an enzyme and suggest how each could affect Km and kcat. 

C8.  Links and References

Mathcad:  Effect of pH on enzyme catalysis (by Paul Krause, Chemistry Department, Univ. of Central Arkansas.

  1. Cornish-Bowden, Athel.  Why is uncompetitive inhibition so rare?  FEBS Letters. 203, 3 (1986)

  2. Cornish-Bowden, Athel.  Teaching Enzyme Kinetics and Mechanism in the 21st Century.   Beilstein Symposium on Experimental Standard Conditions of Enzyme Characterizations (ESCEC).  Pg 3, September 23-26 (2007)

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