Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

19. Enzymes

Enzyme Inhibition

GOB Chemistry

19. Enzymes

Enzyme Inhibition

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1:39 minutes

Problem 28a

Textbook Question

Explain how the following changes affect the rate of an enzyme-catalyzed reaction in the presence of an uncompetitive inhibitor:
(a) increasing the substrate concentration at a constant inhibitor concentration

Verified step by step guidance

Understand the role of an uncompetitive inhibitor: An uncompetitive inhibitor binds only to the enzyme-substrate complex, not to the free enzyme. This binding prevents the enzyme from converting the substrate into the product, effectively reducing the maximum reaction rate (V_max) and the apparent Michaelis constant (K_m).

Recognize the effect of increasing substrate concentration: In a typical enzyme-catalyzed reaction without inhibitors, increasing the substrate concentration increases the reaction rate until the enzyme becomes saturated. However, in the presence of an uncompetitive inhibitor, the inhibitor binds more effectively as the enzyme-substrate complex concentration increases.

Analyze the impact on reaction rate: As substrate concentration increases, more enzyme-substrate complexes form, which allows more uncompetitive inhibitor to bind. This further reduces the effective number of active enzyme-substrate complexes available for catalysis, limiting the reaction rate.

Relate this to V_max and K_m: The presence of the uncompetitive inhibitor decreases both V_max and K_m. Even though increasing substrate concentration would normally increase the reaction rate, the inhibitor's effect prevents the reaction from reaching the uninhibited V_max.

Conclude the overall effect: Increasing the substrate concentration at a constant inhibitor concentration will not overcome the inhibition caused by the uncompetitive inhibitor. Instead, the reaction rate will approach a lower maximum rate (inhibited V_max) than it would in the absence of the inhibitor.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Enzyme Kinetics

Enzyme kinetics is the study of the rates of enzyme-catalyzed reactions. It involves understanding how various factors, such as substrate concentration and inhibitors, influence the speed of these reactions. The Michaelis-Menten model is often used to describe the relationship between substrate concentration and reaction rate, providing a framework for analyzing how enzymes function under different conditions.

Uncompetitive Inhibition

Uncompetitive inhibition occurs when an inhibitor binds to the enzyme-substrate complex, preventing the complex from releasing products. This type of inhibition decreases both the maximum reaction rate (Vmax) and the apparent Michaelis constant (Km), effectively altering the enzyme's activity. In the presence of an uncompetitive inhibitor, increasing substrate concentration can still lead to a higher reaction rate, but the maximum rate achieved will be lower than without the inhibitor.

Substrate Concentration Effects

The concentration of substrate plays a critical role in enzyme-catalyzed reactions. As substrate concentration increases, the rate of reaction typically increases until a maximum rate is reached, where all enzyme active sites are occupied. In the context of uncompetitive inhibition, while increasing substrate concentration can enhance the reaction rate, the presence of the inhibitor means that the maximum rate will be lower than it would be without the inhibitor, illustrating the complex interplay between substrate levels and enzyme activity.

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Textbook Question

What kind of inhibition (uncompetitive, competitive, or irreversible) is present in each of the following:

a. Penicillin is used to treat certain bacterial infections. Penicillin is effective because it binds to the enzyme glycopeptide transpeptidase and does not dissociate.

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Textbook Question

What kind of inhibition (uncompetitive, competitive, or irreversible) is present in each of the following:

c. The antibiotic deoxycycline inhibits the bacterial enzyme collagenase, slowing bacterial growth. Deoxycycline does not fit into the active site of collagenase and binds elsewhere on the enzyme.

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Textbook Question

One mechanism by which lead exerts its poisonous effect on enzymes can be stopped by chelation therapy with EDTA. Describe this type of lead poisoning and explain why it is reversible.

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Textbook Question

What kind of reaction product might be a competitive inhibitor for the enzyme that catalyzes its formation?

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Textbook Question

Explain how the following changes affect the rate of an enzyme-catalyzed reaction in the presence of an uncompetitive inhibitor:

(b) decreasing the inhibitor concentration at a constant substrate concentration.

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Textbook Question

Indicate whether each of the following describes a competitive or a noncompetitive enzyme inhibitor:

a. The inhibitor has a structure similar to the substrate.

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Textbook Question

Indicate whether each of the following describes a competitive or a noncompetitive enzyme inhibitor:

d. The structure of the inhibitor is not similar to the substrate.

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Textbook Question

Methanol and ethanol are oxidized by alcohol dehydrogenase. In methanol poisoning, ethanol is given intravenously to prevent the formation of formaldehyde that has toxic effects.

b. Would ethanol compete for the active site or bind to a different site?

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