Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

25. Condensation Chemistry

Condensation Reactions

Organic Chemistry

25. Condensation Chemistry

Condensation Reactions

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1:29 minutes

Problem 89b

Textbook Question

The following compound has been found to be an inhibitor of penicillinase. The enzyme can be reactivated by hydroxylamine (NH₂OH). Propose a mechanism to account for the reactivation.

Verified step by step guidance

Identify the functional groups in the inhibitor compound that could interact with the enzyme penicillinase. Look for electrophilic centers or reactive groups that could form a covalent bond with the enzyme.

Understand the role of hydroxylamine (NH2OH) in the reactivation process. Hydroxylamine is a nucleophile, meaning it can attack electrophilic centers in the inhibitor-enzyme complex to break the covalent bond.

Propose the first step of the mechanism: Hydroxylamine (NH2OH) attacks the electrophilic center in the inhibitor-enzyme complex. This could involve a nucleophilic attack on a carbonyl carbon or another electrophilic atom in the inhibitor.

Describe the bond-breaking process: The nucleophilic attack by hydroxylamine leads to the cleavage of the covalent bond between the inhibitor and the enzyme. This restores the enzyme's active site to its original state.

Conclude the mechanism: The inhibitor is released as a byproduct, and the enzyme is reactivated, ready to perform its catalytic function again. Ensure to account for any proton transfers or intermediate steps that stabilize the reaction.

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Key Concepts

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

Enzyme Inhibition

Enzyme inhibition refers to the process by which a molecule (inhibitor) decreases or halts the activity of an enzyme. In the context of penicillinase, an enzyme that breaks down penicillin, inhibitors can bind to the enzyme and prevent it from catalyzing its reaction. Understanding the type of inhibition (competitive, non-competitive, or irreversible) is crucial for proposing mechanisms of reactivation.

Hydroxylamine Reactivation

Hydroxylamine (NH2OH) is a nucleophilic reagent that can reactivate certain enzymes by modifying specific amino acid residues. In the case of penicillinase, hydroxylamine can cleave the covalent bond formed between the enzyme and the inhibitor, restoring the enzyme's active site. This process is essential for understanding how the enzyme can regain its function after being inhibited.

Mechanism of Enzyme Action

The mechanism of enzyme action describes the step-by-step process by which an enzyme catalyzes a reaction. This includes substrate binding, transition state formation, and product release. A clear understanding of these steps is necessary to propose a detailed mechanism for how hydroxylamine reactivates penicillinase, including the specific interactions and changes occurring at the molecular level.

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Catalytic antibodies catalyze a reaction by forcing the conformation of the substrate in the direction of the transition state. The synthesis of the antibody is carried out in the presence of a transition state analog—a stable molecule that structurally resembles the transition state. This causes an antibody to be generated that recognizes and binds to the transition state, thereby stabilizing it. For example, the following transition state analog has been used to generate a catalytic antibody that catalyzes the hydrolysis of the structurally similar ester:

a. Draw a possible transition state for the hydrolysis reaction.

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The following compound has been found to be an inhibitor of penicillinase. The enzyme can be reactivated by hydroxylamine (NH₂OH). Propose a mechanism to account for the inhibition.

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