Question

Draw the structures of the two dipeptides that can be formed from serine and alanine.

Short answer

The structures of the two dipeptides formed from serine and alanine are: 1. Ser-Ala: \(H_2N-CH(CH_2OH)-CO-NH-CH(CH_3)-COOH\) 2. Ala-Ser: \(H_2N-CH(CH_3)-CO-NH-CH(CH_2OH)-COOH\)

Step-by-step solution

Structure of Serine

Serine (Ser) has the following structure: \(NH_2-CH(CH_2OH)-COOH\) Alanine:

Structure of Alanine

Alanine (Ala) has the following structure: \(NH_2-CH(CH_3)-COOH\) Now, let's form dipeptides by combining them in two possible orders:

Formation of Ser-Ala Dipeptide

To form the Ser-Ala dipeptide, we need to connect the carboxyl group (COOH) of the serine and the amino group (NH2) of the alanine. This connection occurs when the hydrogen of the amino group (NH2) of alanine and the hydroxyl group (OH) of the carboxyl group of serine get removed, forming a peptide bond. So, the Ser-Ala dipeptide will have the following structure: \(H_2N-CH(CH_2OH)-CO-NH-CH(CH_3)-COOH\)

Formation of Ala-Ser Dipeptide

To form the Ala-Ser dipeptide, we need to connect the carboxyl group (COOH) of the alanine and the amino group (NH2) of the serine. This connection occurs when the hydrogen of the amino group (NH2) of serine and the hydroxyl group (OH) of the carboxyl group of alanine get removed, forming a peptide bond. So, the Ala-Ser dipeptide will have the following structure: \(H_2N-CH(CH_3)-CO-NH-CH(CH_2OH)-COOH\) In conclusion, the structures of the two dipeptides formed from serine and alanine are: 1. Ser-Ala: \(H_2N-CH(CH_2OH)-CO-NH-CH(CH_3)-COOH\) 2. Ala-Ser: \(H_2N-CH(CH_3)-CO-NH-CH(CH_2OH)-COOH\)

Key concepts

Serine and Alanine Dipeptides

Understanding the specifics of how dipeptides are constructed can enhance a student's comprehension of protein formation. Serine and alanine are both amino acids, the building blocks of proteins. When these two amino acids bond together, they can form two different dipeptides based on their sequence. In chemistry, the sequence in which molecules are joined can significantly influence the structure and properties of the resulting compound. In the case of the dipeptides composed of serine and alanine, one would be termed a Ser-Ala dipeptide, while the other would be termed an Ala-Ser dipeptide.

The Ser-Ala dipeptide is formed when the carboxyl group of serine connects with the amino group of alanine. Conversely, the Ala-Ser version is when alanine's carboxyl group bonds with serine's amino group. These subtle differences can result in varied properties and behaviors, which are crucial in biochemical processes and protein engineering. When studying dipeptides, recognizing the amino acids' unique structures—serine with its hydroxymethyl group and alanine with its methyl group—is key to predicting dipeptide characteristics.

Peptide Bond

A peptide bond is a chemical bond that is common to all proteins, connecting one amino acid to another. It's a covalent bond formed between the carboxyl group of one amino acid and the amino group of an adjacent amino acid. During this process, a molecule of water is released—a reaction known as a condensation or dehydration synthesis reaction.

Understanding the peptide bond formation is essential for several reasons. It's the backbone of protein structure; it determines protein conformation; and it's involved in various biochemical reactions. The peptide bond is also rigid and planar, imposing a fixed structure that can be essential for the function of proteins. These facts underscore the peptide bond's importance in maintaining the precise structure necessary for a protein's biological activity.

Amino Acids Sequences

Amino acids are organic compounds that combine to form proteins, which are the workhorses in the cells, carrying out various functions necessary for life. A protein's specific function is determined by its amino acid sequence, informally referred to as its primary structure. Sequences dictate how a protein will fold into a three-dimensional shape essential for its function. Each amino acid has a side chain, which can be polar, nonpolar, acidic, or basic, and influences how they interact with each other and with the environment within a protein.

Introducing concepts such as polarity and side-chain interactions can help students better understand why particular amino acids are found in specific locations within proteins. For instance, in the creation of the dipeptide from serine and alanine, the hydroxyl side chain of serine and the methyl side chain of alanine will interact differently with their surroundings, making even simple dipeptide formation an intricate example of biochemical complexity.