Chapter Three: Enzymes

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Presentation transcript:

Chapter Three: Enzymes

Inhibition of Enzymes Can be irreversible (metals) or reversible (product, substrate, salt, etc.) Types of inhibition: Competitive Noncompetitive Uncompetitive Substrate Inhibition

Competitive Inhibition Inhibitor is an analog of the substrate, and binds to the active site of the enzyme.

Mechanism of Competitive Inhibition What assumption have we make in defining the parameters on the right?

Competitive Inhibition Product formation rate is given by: What is the magnitude of relative to and what will be the effect on v? How could you run a process to minimize the effects of this type of inhibition?

Competitive Inhibition Vm is unchanged 1/Vm -1/Km -1/Km,app 1/[S]

Noncompetitive Inhibition Inhibitor binds to the enzyme and/or enzyme-substrate complex, but not at the active site. However, the enzyme affinity for substrate is reduced.

Mechanism of Noncompetitive Inhibition

Noncompetitive Inhibition Product formation rate is given by: Question: What is the magnitude of Vm,app relative to Vm, and what will be the effect on v? How can you moderate the effects of this type of inhibition.

Noncompetitive Inhibition 1/Vm,app 1/Vm -1/Km 1/[S] Km is unchanged

Uncompetitive Inhibition Inhibitor binds only to ES complex, and not to E alone.

Uncompetitive Inhibition Rate is given by: What is the magnitude of Vm,app relative to Vm? What is the magnitude of relative to ?

Uncompetitive Inhibition 1/Vm,app 1/Vm -1/Km 1/[S] -1/Km,app

Substrate Inhibition Substrate binds to ES complex. 14

Substrate Inhibition No substrate inhibition v Substrate inhibition S The maximum substrate concentration resulting in maximum reaction rate is:

Summary of Enzyme Inhibition 16

Example 3.2 17

Example 3.2 18

Example 3.2 19

Example 3.3 20

Example 3.3 21