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

29. Amino Acids

Amino Acid Chart

Organic Chemistry

29. Amino Acids

Amino Acid Chart

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2:47 minutes

Problem 38

Textbook Question

The first amino acid in the pentapeptide of Figure 26.50, Pyr, is not one of the 20 amino acids in Table 26.1. Based on the following structure of Pyr, from which natural amino acid is it likely derived?

Verified step by step guidance

Examine the structure of Pyr provided in the image. It consists of a five-membered ring with a nitrogen atom and a carboxylic acid group attached to the ring.

Identify the functional groups present in the structure. The five-membered ring is a lactam, which is a cyclic amide. The presence of the carboxylic acid group suggests it is an amino acid derivative.

Compare the structure of Pyr to the structures of the 20 standard amino acids. Look for similarities in the ring structure and functional groups.

Recognize that the five-membered ring with a nitrogen atom is characteristic of the amino acid proline, which has a pyrrolidine ring.

Conclude that Pyr is likely derived from proline, as the structure resembles a modified proline with an additional carbonyl group forming a lactam.

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Key Concepts

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

Amino Acids and Their Derivatives

Amino acids are organic compounds that serve as the building blocks of proteins. There are 20 standard amino acids, each with a unique side chain that determines its properties. Some amino acids can undergo modifications or derivations, leading to the formation of non-standard amino acids, such as Pyr, which may be derived from natural amino acids through post-translational modifications or biosynthetic pathways.

Peptide Structure

Peptides are short chains of amino acids linked by peptide bonds. The sequence and composition of amino acids in a peptide determine its structure and function. Understanding the structure of a peptide, including any non-standard amino acids, is crucial for identifying its origin and potential biological roles, as well as for predicting its interactions with other biomolecules.

Biosynthesis of Amino Acids

The biosynthesis of amino acids involves various metabolic pathways that convert simple precursors into amino acids. Some amino acids can be synthesized from others through transamination or other enzymatic reactions. Recognizing the pathways and precursors involved in amino acid synthesis is essential for deducing the likely natural amino acid from which a non-standard amino acid, like Pyr, is derived.

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