Question

(a) What amino acids would be obtained by hydrolysis of the following tripeptide? (b) How many different tripeptides can be made from the amino acids glycine, serine, and glutamic acid? Give the abbreviation for each of these tripeptides, using the threeletter codes and one-letter codes for the aminoacids.

Short answer

For part (a), the proper approach is to identify the amino acids within the given tripeptide and list their names and abbreviations after hydrolysis, however, the specific tripeptide is not provided in the question. For part (b), there are a total of 27 different tripeptides that can be formed using glycine (Gly, G), serine (Ser, S), and glutamic acid (Glu, E). The possible tripeptide combinations and their abbreviations are as follows: GGG, GGS, GGE, GSG, GSS, GSE, GEG, GES, GEE, SGG, SGS, SGE, SSG, SSS, SSE, SEG, SES, SEE, EGG, EGS, EGE, ESG, ESS, ESE, EEG, EES, EEE.

Step-by-step solution

Part (a): Identify the amino acids in the tripeptide

The given tripeptide is not provided in the exercise statement. However, the general approach to solve this part is to recognize the amino acids within the tripeptide molecule. Hydrolysis of a tripeptide will break the peptide bonds and leaves you with three individual amino acids. The student can list down the names and abbreviations of the amino acids obtained from the hydrolysis.

Part (b): Compute the number of different tripeptides and their abbreviations

To calculate the number of different tripeptides that can be formed using glycine (Gly, G), serine (Ser, S), and glutamic acid (Glu, E), we can utilize the permutation formula because the order of amino acids matters in a peptide sequence. There are 3 positions in a tripeptide, so for each position, there are 3 possible amino acids that can be placed there; therefore, we have: Total number of tripeptides = 3 x 3 x 3 = 27 tripeptides Now, let's list all possible tripeptides using the three-letter codes and the one-letter code: 1. Gly-Gly-Gly (GGG) 2. Gly-Gly-Ser (GGS) 3. Gly-Gly-Glu (GGE) 4. Gly-Ser-Gly (GSG) 5. Gly-Ser-Ser (GSS) 6. Gly-Ser-Glu (GSE) 7. Gly-Glu-Gly (GEG) 8. Gly-Glu-Ser (GES) 9. Gly-Glu-Glu (GEE) 10. Ser-Gly-Gly (SGG) 11. Ser-Gly-Ser (SGS) 12. Ser-Gly-Glu (SGE) 13. Ser-Ser-Gly (SSG) 14. Ser-Ser-Ser (SSS) 15. Ser-Ser-Glu (SSE) 16. Ser-Glu-Gly (SEG) 17. Ser-Glu-Ser (SES) 18. Ser-Glu-Glu (SEE) 19. Glu-Gly-Gly (EGG) 20. Glu-Gly-Ser (EGS) 21. Glu-Gly-Glu (EGE) 22. Glu-Ser-Gly (ESG) 23. Glu-Ser-Ser (ESS) 24. Glu-Ser-Glu (ESE) 25. Glu-Glu-Gly (EEG) 26. Glu-Glu-Ser (EES) 27. Glu-Glu-Glu (EEE) These are the 27 different tripeptides that can be formed using glycine, serine, and glutamic acid, along with their abbreviations in the three-letter codes and one-letter codes.

Key concepts

Understanding Hydrolysis

Hydrolysis is a chemical reaction where a molecule is broken down by water. In the context of tripeptides, hydrolysis involves breaking the peptide bonds that link amino acids together. This reaction essentially reverses the process of forming a tripeptide, resulting in the release of the individual amino acids that were originally connected.

When a tripeptide undergoes hydrolysis, each peptide bond is targeted and cleaved. With each break, water molecules are consumed, adding hydrogen to one fragment and hydroxide to another. This results in the breakdown of the tripeptide into its constituent amino acids.

In essence, if a tripeptide consists of glycine, serine, and glutamic acid, hydrolysis will yield these three amino acids. This process is fundamental in protein digestion and the recycling of amino acids in living organisms.

Introduction to Amino Acids

Amino acids are the building blocks of proteins. There are 20 standard amino acids that create the vast array of proteins found in organisms. Each amino acid has a basic structure consisting of a central carbon atom, an amino group (\( NH_2 \)), a carboxyl group (\( COOH \)), and a variable R group or side chain. This side chain determines the unique characteristics and properties of each amino acid.

In this exercise, we focus on three specific amino acids: glycine, serine, and glutamic acid.

• Glycine (Gly, G) is the simplest amino acid with a hydrogen atom as its R group.
• Serine (Ser, S) has a side chain that contains a hydroxymethyl group (\( CH_2OH \)).
• Glutamic acid (Glu, E) features a side chain with a carboxylic acid group (\( CH_2.CH_2.COOH \)).

The properties of these amino acids including their side chains play a crucial role in the shape and function of proteins they form.

Peptide Bonds Explained

Peptide bonds are the chemical bonds that link amino acids together to form peptides and proteins. This bond is formed through a condensation reaction, where a molecule of water is released as the carboxyl group of one amino acid reacts with the amino group of another.

The resulting bond is a covalent bond which is very strong and stabilizes the structural formation of proteins. Peptide bonds are essential for protein synthesis, allowing amino acids to form chains that can fold into complex structures, which contribute to their function.

In the context of our exercise, the tripeptide made from glycine, serine, and glutamic acid is held together by two peptide bonds. Hydrolysis would break these bonds, resulting in the separation of the individual amino acids.

Applying the Permutation Formula

The permutation formula is a mathematical way to determine the number of possible arrangements of a set of items where order matters. For our amino acid problem, each position in a tripeptide can have one of three amino acids: glycine, serine, or glutamic acid.

The permutation formula for this situation is simple: multiply the number of choices for each position. Thus, \( 3 \times 3 \times 3 = 27 \), indicating that you can form 27 unique tripeptides.

These permutations account for the different possible orders in which the amino acids can be linked, such as Gly-Gly-Ser, Ser-Gly-Glu, etc. This explains why, even with just three amino acids, so many different structures are possible. This principle is vital in understanding diversity in protein sequences and their functions in biological systems.