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

Proteins and Amino Acids

Organic Chemistry

29. Amino Acids

Proteins and Amino Acids

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9:13 minutes

Problem 35

Textbook Question

a. Calculate the overall yield of bradykinin when the yield for the addition of each amino acid to the chain is 70%.
b. What would be the overall yield of a peptide containing 15 amino acids if the yield for the incorporation of each is 80%

Verified step by step guidance

Step 1: Understand the problem. The overall yield of a peptide synthesis is calculated by multiplying the yield of each step (amino acid addition) for the total number of steps. This is because each step has a probability of success, and the overall yield is the product of these probabilities.

Step 2: For part (a), identify the number of amino acids in bradykinin. Bradykinin is a peptide composed of 9 amino acids. The yield for each step is given as 70%, which can be expressed as 0.70 in decimal form.

Step 3: Use the formula for overall yield: \( \text{Overall Yield} = (\text{Yield per step})^{\text{Number of steps}} \). Substitute the values for bradykinin: \( \text{Overall Yield} = (0.70)^9 \).

Step 4: For part (b), identify the number of amino acids in the peptide, which is 15. The yield for each step is given as 80%, or 0.80 in decimal form. Use the same formula: \( \text{Overall Yield} = (\text{Yield per step})^{\text{Number of steps}} \). Substitute the values: \( \text{Overall Yield} = (0.80)^{15} \).

Step 5: To complete the problem, calculate the numerical values for both parts (a) and (b) using the formulas provided. This will give the overall yield for bradykinin and the 15-amino-acid peptide.

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Key Concepts

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

Peptide Synthesis Yield

In peptide synthesis, the yield refers to the efficiency of incorporating each amino acid into the growing peptide chain. It is typically expressed as a percentage, indicating the fraction of successful reactions compared to the total number of attempts. Understanding yield is crucial for predicting the final amount of peptide produced after multiple coupling reactions.

Multiplicative Yield Calculation

When calculating the overall yield of a multi-step synthesis process, the yields of each step are multiplied together. This is because each step's yield affects the subsequent steps; if one step has a lower yield, it reduces the amount of product available for the next step. This concept is essential for determining the final yield of complex molecules like peptides.

Bradykinin Structure

Bradykinin is a peptide composed of a specific sequence of amino acids, typically consisting of nine residues. Understanding its structure is important for calculating yields, as each amino acid addition contributes to the final sequence. The specific sequence and the number of amino acids directly influence the overall yield calculations in peptide synthesis.

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Textbook Question

Predict the products of the following reactions.

(e)

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Predict the products of the following reactions.

(f)

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Show how you would synthesize any of the standard amino acids from each starting material. You may use any necessary reagents.

(c)

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For each compound,

1. name the functional group.

2. show what compound(s) result from complete hydrolysis.

(c)

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What dipeptides would be formed by heating a mixture of valine and N-protected leucine?

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Proof that an imine was formed between aldolase and its substrate was obtained by using D-fructose-1,6-bisphosphate labeled at the C-2 position with ¹⁴C as the substrate. NaBH₄ was added to the reaction mixture. A radioactive product was isolated from the reaction mixture and hydrolyzed in an acidic solution. Draw the structure of the radioactive product obtained from the acidic solution. (Hint: NaBH₄ reduces an imine linkage.)

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Draw the product obtained when a lysine side chain in a polypeptide reacts with maleic anhydride.

Textbook Question

Draw the tetrapeptide Ala-Thr-Asp-Asn and indicate the peptide bonds.

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