Ch. 21 - Amino Acids, Peptides, and Proteins

Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook

Bruice 8th Edition

Ch. 21 - Amino Acids, Peptides, and Proteins

Problem 26

Chapter 22, Problem 26

Draw the tetrapeptide Ala-Thr-Asp-Asn and indicate the peptide bonds.

Verified step by step guidance

Step 1: Understand the structure of each amino acid. Alanine (Ala) has a methyl group (-CH₃) as its side chain, Threonine (Thr) has a hydroxyl group (-CH(OH)CH₃), Aspartic acid (Asp) has a carboxylic acid group (-CH₂COOH), and Asparagine (Asn) has an amide group (-CH₂CONH₂).

Step 2: Identify the general structure of an amino acid. Each amino acid has an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and a unique side chain (R group) attached to the central carbon (α-carbon).

Step 3: Link the amino acids in the specified order (Ala-Thr-Asp-Asn) by forming peptide bonds. A peptide bond is formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH₂) of the next amino acid, releasing a molecule of water (H₂O) in a condensation reaction.

Step 4: Draw the tetrapeptide structure. Start with Alanine, connect its carboxyl group to the amino group of Threonine via a peptide bond, then connect Threonine's carboxyl group to the amino group of Aspartic acid, and finally connect Aspartic acid's carboxyl group to the amino group of Asparagine. Ensure the side chains of each amino acid are correctly represented.

Step 5: Indicate the peptide bonds in the structure. Highlight the C=O and N-H bonds that form the peptide linkages between each pair of amino acids. These bonds are the defining feature of the peptide backbone.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Peptide Bonds

Peptide bonds are covalent bonds that link amino acids together in a protein or peptide chain. They form through a dehydration synthesis reaction, where the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water. This bond is crucial for the structure of proteins, as it determines the sequence and arrangement of amino acids.

Amino Acids

Amino acids are the building blocks of proteins, each consisting of a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group). The side chain determines the properties of each amino acid, influencing the overall structure and function of the resulting peptide or protein. In the context of the question, the specific amino acids Ala (Alanine), Thr (Threonine), Asp (Aspartic acid), and Asn (Asparagine) are to be represented.

Tetrapeptide Structure

A tetrapeptide is a peptide composed of four amino acids linked by peptide bonds. The sequence of amino acids in a tetrapeptide is significant, as it dictates the peptide's properties and biological function. In this case, the tetrapeptide Ala-Thr-Asp-Asn must be drawn to show the correct order and connections, highlighting the peptide bonds between each pair of amino acids.

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What alkyl halide is used in the acetamidomalonic ester synthesis to prepare

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Esterase is an enzyme that catalyzes the hydrolysis of esters. It hydrolyzes esters of l-amino acids more rapidly than esters of D-amino acids. How can this enzyme be used to separate a racemic mixture of amino acids?

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Textbook Question

An opioid pentapeptide has the following structure: Tyr-Cys-Gly-Phe-Cys

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b. Write its structure following mild oxidation.

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Textbook Question

Which bonds in the backbone of a peptide can rotate freely?

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