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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Problem 48a

Textbook Question

Oxaloacetate is an inhibitor of succinate dehydrogenase.

a. Would you expect oxaloacetate to be a competitive or a noncompetitive inhibitor? Why?

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Understand the difference between competitive and noncompetitive inhibition: Competitive inhibitors bind to the active site of the enzyme, competing with the substrate, while noncompetitive inhibitors bind to a different site on the enzyme, altering its function without directly competing with the substrate.

Analyze the role of oxaloacetate in the context of succinate dehydrogenase. Oxaloacetate is structurally similar to succinate, the substrate for succinate dehydrogenase, which suggests it may compete for the active site.

Consider the mechanism of inhibition: If oxaloacetate binds to the active site of succinate dehydrogenase, it would prevent succinate from binding, indicating competitive inhibition.

Evaluate whether oxaloacetate could bind elsewhere on the enzyme: If oxaloacetate binds to a site other than the active site and changes the enzyme's shape or function, it would indicate noncompetitive inhibition.

Conclude based on the evidence: Since oxaloacetate is structurally similar to succinate, it is likely a competitive inhibitor, as it competes with succinate for the active site of succinate dehydrogenase.

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Key Concepts

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

Competitive Inhibition

Competitive inhibition occurs when an inhibitor competes with the substrate for binding to the active site of an enzyme. In this scenario, the presence of the inhibitor can be overcome by increasing the concentration of the substrate. This type of inhibition typically results in an increase in the apparent Km (Michaelis constant) of the enzyme, while Vmax (maximum reaction velocity) remains unchanged.

Noncompetitive Inhibition

Noncompetitive inhibition happens when an inhibitor binds to an enzyme at a site other than the active site, altering the enzyme's function regardless of substrate concentration. This means that even if the substrate is present, the inhibitor can still prevent the enzyme from catalyzing the reaction effectively. In this case, the Vmax decreases, but the Km remains the same.

Oxaloacetate's Role

Oxaloacetate is a four-carbon dicarboxylic acid that plays a crucial role in the citric acid cycle. As an inhibitor of succinate dehydrogenase, it can affect the enzyme's activity by either competing with succinate for the active site or binding elsewhere. Understanding its mechanism of inhibition is essential for determining whether it acts as a competitive or noncompetitive inhibitor.

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