Problem 79 - A Complete Resource Book in Chemistry for JEE Main

Question

Sanger's reagent is used for the identification of (a) C- terminal of a peptide chain (b) \(\mathrm{N}-\) terminal of a peptide chain (c) number of amino acids in a peptide chain (d) side chain of amino acids

Step-by-Step Solution

Answer

Sanger's reagent is used for identifying the N-terminal of a peptide chain.

Step 1: Understanding Sanger's Reagent

Sanger's reagent, also known as 1-fluoro-2,4-dinitrobenzene (FDNB), is primarily used in biochemistry for chain termination sequencing. It reacts specifically with the N-terminal amino acid of a peptide to form a dinitrophenyl derivative.

Step 2: Application to Peptide Chains

Given that Sanger's reagent reacts with the N-terminal amino acid, it allows for the identification of this terminus in peptide chains. This process helps determine the presence and identity of the N-terminal amino acid, though not the side chain, C-terminal, or count of amino acids directly.

Step 3: Analyzing Options

Out of the given options, you need to identify where Sanger's reagent is applicable. Option (b), the identification of the N-terminal of a peptide chain, aligns perfectly with the use of Sanger's reagent.

Key Concepts

N-terminal identification

Sanger's reagent is a powerful tool in biochemistry for identifying the N-terminal amino acid of a peptide chain. But what does this mean? The N-terminal is the starting point of a peptide chain. Sanger's reagent, scientifically known as 1-fluoro-2,4-dinitrobenzene (FDNB), reacts with this terminal amino group to form a labeled derivative. This reaction is crucial because it allows scientists to pinpoint which amino acid is at the beginning of the chain.

In practical terms, once the N-terminal reacts with Sanger's reagent, it can then be separated and analyzed, often by techniques such as chromatography. The resulting dinitrophenyl (DNP) derivative provides a unique fingerprint for each amino acid. Thus, this method gives clear information about only the first amino acid of the sequence—not the entire sequence or any other position within the peptide chain.

peptide chain analysis

Peptide chain analysis is a broader term encompassing several techniques to understand the composition and structure of peptides. The process involves breaking down the peptide into smaller parts, or even single amino acids, to analyze their order and structure.

Within the context of N-terminal identification, knowing the identity of amino acids at the ends of peptide chains can provide valuable clues to the overall sequence. While Sanger's reagent targets the N-terminal, the complete analysis of a peptide often involves combining several methods. These may include enzymatic digestion, other chemical reactions, and the use of spectrometry.

In essence, by understanding each component, from the identity of terminal amino acids to the sequence of internal residues, scientists can unravel the entire peptide's structure, which is critical for biochemical research and understanding protein function.

biochemistry

Biochemistry is the science of the chemical processes within living organisms. One of its key areas is the study of proteins and peptides, which are vital biomolecules. Understanding their structure and the sequence of amino acids allows researchers to gain insights into how proteins function in life processes.

Sanger's reagent, a biochemical tool, showcases the importance of chemical methods in biochemistry. It highlights how simple chemical reactions can yield important data about larger biological structures. This kind of analysis is crucial for many applications, from drug development to understanding diseases at a molecular level.

Biochemistry doesn’t just stop at identifying the peptides; it links these findings with biological functions. Whether it’s an enzyme’s role in catalysis or a receptor's function in cell signaling, understanding the structure down to specific terminals is fundamental to our broader understanding of life sciences.