Title: Enzyme Kinetics II
1Enzyme Kinetics II
2Kinetic data cannot unambiguously establish a
reaction mechanism.
Although a phenomenological description can be
obtained the nature of the reaction intermediates
remain indeterminate and other independent
measurements are needed.
3Reaction MechanismsA Sequential Reactions
- All substrates must combine with enzyme before
reaction can occur
4Bisubstrate reactions
5Random Bisubstrate Reactions
6Ping-Pong Reactions
- Group transfer reactions
- One or more products released before all
substrates added
7Inhibition kinetics
- There are three types of inhibition kinetics
competitive, - mixed and uncompetitive.
- Competitive- Where the inhibitor competes with
the substrate.
8Competitive Inhibition
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11HIV protease inhibitors
12Competitive Inhibition Lineweaver-Burke Plot
13Uncompetitive Inhibition
14Uncompetitive Inhibition Lineweaver-Burke Plot
15Mixed inhibition
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17Mixed inhibition is when the inhibitor binds to
the enzyme at a location distinct from the
substrate binding site. The binding of the
inhibitor will either alter the KM or Vmax or
both.
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19The effect of pH on kinetic parameters
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22Lecture 17Tuesday 10/21/08Enzyme Kinetics /
Exam II Minireview