Question

(a) How many tripeptides can be made from glycine, alanine, and leucine, using each amino acid only once per tripeptide? (b) Write the structural formulas of these tripeptides and name them in the shorthand abbreviation used for showing amino acid sequences.

Short answer

Provide their shorthand names and structural formulas. Answer: There are 6 possible tripeptides that can be made using glycine (G), alanine (A), and leucine (L), with each amino acid being used once per tripeptide. The shorthand names and structural formulas are as follows: 1. GAL: NH2-CH2-COOH, NH-CH3-COOH, NH-CH(C4H9)-COOH 2. GLA: NH2-CH2-COOH, NH-CH(C4H9)-COOH, NH-CH3-COOH 3. AGL: NH2-CH3-COOH, NH-CH2-COOH, NH-CH(C4H9)-COOH 4. ALG: NH2-CH3-COOH, NH-CH(C4H9)-COOH, NH-CH2-COOH 5. LGA: NH2-CH(C4H9)-COOH, NH-CH2-COOH, NH-CH3-COOH 6. LAG: NH2-CH(C4H9)-COOH, NH-CH3-COOH, NH-CH2-COOH

Step-by-step solution

Determine the number of possible combinations

We have three different amino acids: glycine (G), alanine (A), and leucine (L). To form a tripeptide, we need to select one amino acid for each position in the sequence. There are 3 amino acids to choose from for the first position, 2 for the second position (since we can't repeat the one we used in the first position), and only 1 for the last position. This leads us to the following equation: Total combinations = 3 × 2 × 1 = 6 So, there are 6 possible tripeptides that can be made using glycine, alanine, and leucine, with each amino acid used once.

Find the possible combinations and their shorthand names

Now that we know there are 6 possible combinations, let's list them and their shorthand names: 1. Glycine - Alanine - Leucine (GAL) 2. Glycine - Leucine - Alanine (GLA) 3. Alanine - Glycine - Leucine (AGL) 4. Alanine - Leucine - Glycine (ALG) 5. Leucine - Glycine - Alanine (LGA) 6. Leucine - Alanine - Glycine (LAG)

Write the structural formulas for the possible tripeptides

Draw the structural formulas for these tripeptides: 1. Glycine - Alanine - Leucine (GAL): NH2-CH2-COOH | NH-CH3-COOH | NH-CH(C4H9)-COOH 2. Glycine - Leucine - Alanine (GLA): NH2-CH2-COOH | NH-CH(C4H9)-COOH | NH-CH3-COOH 3. Alanine - Glycine - Leucine (AGL): NH2-CH3-COOH | NH-CH2-COOH | NH-CH(C4H9)-COOH 4. Alanine - Leucine - Glycine (ALG): NH2-CH3-COOH | NH-CH(C4H9)-COOH | NH-CH2-COOH 5. Leucine - Glycine - Alanine (LGA): NH2-CH(C4H9)-COOH | NH-CH2-COOH | NH-CH3-COOH 6. Leucine - Alanine - Glycine (LAG): NH2-CH(C4H9)-COOH | NH-CH3-COOH | NH-CH2-COOH In conclusion, there are 6 possible tripeptides that can be created using glycine, alanine, and leucine, with each amino acid being used once. Their shorthand names and structural formulas have been provided.