Draw the structural formula for each of the following peptides:
c. Val—Arg

Verified step by step guidance

1. Identify the amino acids involved in the peptide. In this case, the peptide consists of Valine (Val) and Arginine (Arg).
2. Recall the general structure of an amino acid: an amino group ($\backslash text\{-NH\}\_2$), a carboxyl group ($\backslash text\{-COOH\}$), a hydrogen atom, and a unique side chain (R-group) attached to a central carbon atom (alpha carbon).
3. Determine the side chains for Valine and Arginine. Valine has a branched alkyl side chain ($\backslash text\{-CH(CH\}\_3\backslash text\{)\_2\}$), and Arginine has a guanidino group ($\backslash text\{-CH\}\_2\backslash text\{-CH\}\_2\backslash text\{-NH-C(NH)\_2\}$).
4. Form the peptide bond between the carboxyl group of Valine and the amino group of Arginine. A peptide bond is a covalent bond formed by a condensation reaction, where a molecule of water is removed, linking the carbon of the carboxyl group to the nitrogen of the amino group.
5. Draw the structural formula of the dipeptide Val—Arg, ensuring the peptide bond is correctly represented and the side chains of Valine and Arginine are accurately depicted.

Key Concepts

Peptide Structure

Peptides are short chains of amino acids linked by peptide bonds. The structure of a peptide is determined by the sequence of its constituent amino acids, which influences its properties and functions. Understanding the basic structure of peptides is essential for drawing their structural formulas.

Amino Acids

Amino acids are the building blocks of peptides and proteins, each containing an amino group, a carboxyl group, and a unique side chain (R group). The specific properties of the amino acids, such as polarity and charge, affect the overall structure and function of the peptide. In the case of Val—Arg, valine and arginine are the two amino acids involved.

Peptide Bond Formation

A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water in a condensation reaction. This bond is crucial for linking amino acids together to form peptides. Understanding how peptide bonds are formed is key to accurately representing the structural formula of peptides.