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

1. 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.
2. 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.
3. Step 3: Use the formula for overall yield: \( \text{Overall Yield} = (\text{Yield per step})^{\text{Number of steps}} \). Substitute the values for bradykinin: \( \text{Overall Yield} = (0.70)^9 \).
4. 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: \( \text{Overall Yield} = (0.80)^{15} \).
5. 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.

Key Concepts

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.