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Chapter 17: Problem 26

(a) What are inhibitors? (b) What possible mechanisms account for their effectiveness?

Short Answer

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Answer: Inhibitors are substances that decrease the rate or prevent a chemical reaction by interacting with reactants, such as enzymes or substrates. In enzyme-catalyzed reactions, inhibitors can affect enzyme activity through three main mechanisms: competitive inhibition, non-competitive inhibition, and uncompetitive inhibition. Competitive inhibition involves the inhibitor competing with the substrate for binding to the enzyme's active site, while non-competitive inhibition occurs when the inhibitor binds to a separate allosteric site on the enzyme, causing a conformational change that reduces its affinity for the substrate. Uncompetitive inhibition occurs when the inhibitor binds to the enzyme-substrate complex after substrate binding, resulting in an inactive complex. These mechanisms help control enzyme activity and chemical reactions in various situations.

Step by step solution

01

(a) Definition of Inhibitors

Inhibitors are substances that decrease the rate or prevent a chemical reaction, often by interacting with one or more of the reactants involved in the reaction. In the context of enzyme-catalyzed reactions, inhibitors are molecules that bind to enzymes and decrease their activity.
02

(b) Possible Mechanisms for Inhibitors' Effectiveness

There are several mechanisms through which inhibitors can affect the activity of enzymes or other reactants in a chemical reaction. We will break down three main types of inhibition: competitive inhibition, non-competitive inhibition, and uncompetitive inhibition.
03

Competitive Inhibition

In competitive inhibition, the inhibitor competes with the substrate for binding to the enzyme's active site. In this case, the inhibitor closely resembles the structure of the substrate and binds to the enzyme's active site, preventing the substrate from binding. The inhibitor's effectiveness depends on the concentration of the inhibitor relative to the concentration of the substrate; if the substrate concentration is high, the effect of the inhibitor can be diminished.
04

Non-competitive Inhibition

In non-competitive inhibition, the inhibitor does not compete for the enzyme's active site. The inhibitor binds to a separate site on the enzyme, called the allosteric site, which leads to a conformational change in the enzyme's structure. This change in structure decreases the enzyme's affinity for the substrate, reducing its activity. In non-competitive inhibition, increasing the substrate concentration does not overcome the inhibition.
05

Uncompetitive Inhibition

Uncompetitive inhibition occurs when the inhibitor binds to the enzyme-substrate complex after the substrate has already bound to the enzyme. This interaction results in the formation of an inactive enzyme-substrate-inhibitor complex, which cannot continue the reaction. Like non-competitive inhibition, uncompetitive inhibition is not overcome by increasing the substrate concentration. These different mechanisms of inhibition help explain how inhibitors can effectively control enzyme activity and chemical reactions in various situations.

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Most popular questions from this chapter

or each form of corrosion, other than uniform, do the following: (a) Describe why, where, and the conditions under which the corrosion occurs. (b) Cite three measures that may be taken to prevent or control it.

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