Problem 14 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The number of \(\lambda C=O\) groups present in a tripeptide Asp - Glu Lys is

Step-by-Step Solution

Answer

The tripeptide Asp-Glu-Lys contains four \(C=O\) groups.

Step 1: Understand the Peptide Structure

A tripeptide is made up of three amino acids linked by peptide bonds. In this case, the tripeptide is composed of Aspartic Acid (Asp), Glutamic Acid (Glu), and Lysine (Lys).

Step 2: Identify the Relevant Functional Groups

Each amino acid in a peptide has a \(-COOH\) (carboxylic acid) group and an \(-NH_2\) (amine) group. The \(C=O\) group is part of the carboxylic acid moiety in the peptide bonds.

Step 3: Analyze the Peptide Bonds

When amino acids form a peptide bond, the \(C=O\) group from the carboxylic acid of one amino acid bonds with the amine group of the next amino acid, forming an amide bond \(-CO-NH-\).

Step 4: Count the Amide Linkages

There are two peptide bonds in a tripeptide, and each contains one \(C=O\) group: one between Aspartic Acid and Glutamic Acid, and another between Glutamic Acid and Lysine.

Step 5: Review Any Remaining Carboxylic Acid Groups

Aspartic Acid and Glutamic Acid each have an additional side-chain carboxylic acid group. In total, Asp and Glu contribute two additional \(C=O\) groups to the structure.

Step 6: Add Up All the \\(C=O\\) Groups

In the tripeptide, there are two \(C=O\) groups from the amide bonds and two from the side-chain carboxylic acids, adding to a total of four \(C=O\) groups.

Key Concepts

Tripeptide Structure

A tripeptide is a small protein segment made up of three amino acids linked together by peptide bonds. In the case of the tripeptide Asp-Glu-Lys, it consists of Aspartic Acid (Asp), Glutamic Acid (Glu), and Lysine (Lys). When these amino acids join, they form peptide bonds, which results in a chain-like structure. This sequence is crucial because it determines the function and properties of the peptide.

To understand the tripeptide structure, it helps to visualize the amino acids as links in a chain. They are bonded in a specific order, and each amino acid contributes to the chain with its unique side chain and structure.

When amino acids form a tripeptide, the chemical transformation involves removing water from the connecting carboxyl and amino groups, and forming a stable amide linkage called the peptide bond. It is this sequence and linkage that is paramount in building the primary structure of the proteins.

Amino Acids

Amino acids are organic compounds that serve as the building blocks for proteins. Each amino acid consists of a basic structure, including a carboxyl group (\(-COOH\)), an amino group (\(-NH_2\)), and a distinctive side chain that determines its unique properties.

These side chains can be polar, nonpolar, acidic, or basic, influencing both the behavior of the amino acid and the protein's overall characteristics.
The specific sequence of amino acids in a peptide or protein dictates its shape, role, and function within a biological system.

For instance, Aspartic Acid and Glutamic Acid within the tripeptide provide extra \(C=O\) groups due to their additional carboxylic acid side chains, affecting the tripeptide’s chemical properties.
Understanding the individual properties of amino acids can help in predicting structure and function relationships in larger protein assemblies.

Carboxylic Acid Group

The carboxylic acid group is a key functional group in biochemistry and is frequently found in amino acids. It consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group, written as \(-COOH\). This group is responsible for the acidic property of amino acids, allowing them to donate a proton to the environment.

In the context of peptides like the tripeptide Asp-Glu-Lys, the carboxylic acid group plays a significant role in forming peptide bonds. When the carboxylic acid group from one amino acid forms a peptide bond, it loses an OH group during dehydration, which bonds with an H from the amine group of another amino acid, releasing water and establishing a new link in the peptide chain.

Additionally, certain amino acids like Aspartic Acid and Glutamic Acid possess side chains with extra carboxylic groups, adding additional \(C=O\) functionalities to the peptide. These \(C=O\) groups are crucial in understanding peptide configurations and their chemical behavior, including interactions with other molecules and ions.