Biochemistry: Reactions of amino acids (Part-2)

Learn-at-ease

23 Sept 201509:57

Summary

TLDRThis video from the 'Learn at Ease' YouTube channel delves into the reactions of amino acids, focusing on those catalyzed by the amino group. It covers a range of reactions including acetylation, benzoylation, methylation, and the use of Sanger's reagent for color identification. The video also explores oxidative deamination, reactions with formaldehyde, aromatic aldehydes, ninhydrin, carbon dioxide, and the Verret reaction. It provides a comprehensive guide to the chemical behavior of amino acids, essential for understanding biochemistry.

Takeaways

🧬 Amino acids are organic biomolecules with two oppositely charged functional groups, an amino group and a carboxylic group, attached to the same carbon atom, known as the alpha carbon.
🔍 This video is a continuation of a series discussing the reactions of amino acids, focusing on those that occur due to the involvement of the amino group alone.
🧪 The first reaction discussed is the acylation of amino acids, where the amino acid is isolated by dissolving it in cold alkali and then adding acetic anhydride to obtain an acetylated amino acid.
🌿 The second reaction is the benzoylation, where glycine reacts with benzoic acid to form hippuric acid, a detoxification process in the body.
🔑 The third reaction is methylation, where amino acids are treated with methyl iodide or dimethyl sulfate to obtain betaine, a methylated amino acid.
📚 The fourth reaction involves Sanger's reagent, which condenses with the free amino group to form a DNP amino acid, a bright yellow colored compound used for identification purposes.
💨 The fifth reaction is the reaction with nitrous acid (HNO2), leading to the formation of a hydroxyl acid and the release of nitrogen gas, useful for estimating free amino groups.
🔄 The sixth reaction is oxidative deamination, where amino acids are converted to keto acids and ammonia by oxidative enzyme systems, particularly in the liver and kidneys.
📊 The seventh reaction is the reaction with formaldehyde, where the amino group reacts to form dimethyl all amino acid, which is acidic in nature.
🌈 The eighth reaction is with aromatic aldehydes, leading to the formation of a Schiff base, a molecule with a C=N bond.
🟣 The ninth reaction is with ninhydrin, which forms a purple-colored compound known as Ruheim's purple, a color reaction of amino acids.
🔮 The tenth reaction is the reaction with carbon dioxide, resulting in the formation of N-carboxy amino acids through a condensation reaction.
🟪 The eleventh and final reaction discussed is the Biruté reaction, where copper ions react with the unshared electron pair of nitrogen to form a violet-colored complex, indicating the presence of two CoNH2 groups.

Q & A

What are amino acids and why are they important in biochemistry?
-Amino acids are organic biomolecules that contain an amino group and a carboxylic group attached to the same carbon atom, known as the alpha carbon. They are the building blocks of proteins and are crucial for various biological processes.
What are the two oppositely charged functional groups found in amino acids?
-The two functional groups are the amino group, which is positively charged, and the carboxylic group, which is negatively charged.
What is the significance of the alpha carbon in amino acids?
-The alpha carbon is significant because it is the carbon atom to which both the amino and carboxylic groups are attached, forming the backbone of the amino acid.
Can you explain the concept of 'isolation' in the context of amino acids?
-Isolation in this context refers to the process of separating an amino acid from a mixture when it is dissolved in cold alkali and then treated with acetic anhydride to form an acetylated derivative.
What is benzoyl elation and how does it relate to detoxification in the body?
-Benzoyl elation is the reaction where glycine reacts with benzoic acid to form hippuric acid. This is a detoxification process in the body that neutralizes the toxic benzoic acid.
What is methylation of amino acids and what is its purpose?
-Methylation of amino acids involves the treatment of amino acids with methyl iodide or dimethyl sulfate in an alkaline environment, resulting in the formation of betaines, which are methylated amino acids. This process is part of various biochemical reactions.
What is Sanger's reagent and how does it react with amino acids?
-Sanger's reagent, also known as 1-fluoro-2,4-dinitrobenzene (FDNB), reacts with the free amino group of an amino acid under alkaline conditions to form a DNP amino acid, which is a bright yellow-colored product used for the identification of amino acids.
How does nitrous acid (HNO2) react with amino acids and what is the outcome?
-Nitrous acid reacts with the free amino group of an amino acid, resulting in the formation of a hydroxyl acid, the release of nitrogen gas, and water. This reaction can be used to estimate the number of free amino groups in amino acids, peptides, or proteins.
What is oxidative deamination and what happens during this reaction?
-Oxidative deamination is a two-step reaction where an amino acid is converted to a keto acid and ammonia through the action of oxidative enzyme systems, particularly in the liver and kidneys.
What is the significance of the reaction between amino acids and formaldehyde?
-The reaction between amino acids and formaldehyde is significant because it allows the masking of the positive charge on the amino group by converting the amino acid to a dimethyl all amino acid, which is acidic in nature.
What is a Schiff base and how is it formed during the reaction with aromatic aldehydes?
-A Schiff base is a compound with a C=N double bond formed when an aromatic aldehyde reacts with an amino acid in the presence of an alkali, leading to the formation of a condensation intermediate that loses a water molecule to form the Schiff base.
What is the ninhydrin reaction and its significance in amino acid analysis?
-The ninhydrin reaction is a color reaction where ninhydrin reacts with an amino acid to form a purple-colored compound known as Ruheim's purple or dico hydride Aladin. This reaction is used for the detection and analysis of amino acids.
What is the Verret reaction and how does it relate to the detection of amino acids?
-The Verret reaction is a color reaction where compounds containing two NH2 groups react with copper sulfate to form a violet-colored complex. This reaction is used for the detection of amino acids and peptides.
What is the purpose of the video and who prepared it?
-The purpose of the video is to explain the various chemical reactions of amino acids, focusing on those involving the amino group. It was prepared by Dr. D. R. Paul and Goswami.

Outlines

00:00

🧪 Biochemistry of Amino Acid Reactions

This paragraph introduces the topic of amino acid reactions in biochemistry, focusing on reactions that occur due to the involvement of the amino group. It explains that amino acids have two functional groups, an amino and a carboxylic group, attached to the alpha carbon. The paragraph outlines various reactions such as acylation, benzoylation, methylation, reaction with Sanger's reagent, oxidative deamination, and reaction with formaldehyde. It also mentions the importance of these reactions in understanding the chemical properties of amino acids and their role in biological processes.

05:01

🔍 Further Exploration of Amino Acid Reactions

The second paragraph delves deeper into specific reactions of amino acids, including the formation of Schiff bases with aromatic aldehydes, the color reaction with ninhydrin resulting in Rujisman's purple, and the reaction with carbon dioxide to form N-carboxy amino acids. It also discusses the Verret reaction, which involves the formation of a violet-colored complex with copper ions. The paragraph emphasizes the significance of these reactions in the identification and estimation of amino acids, as well as their broader implications in biochemistry and molecular biology.

Mindmap

Keywords

💡Amino Acids

Amino acids are organic biomolecules that are the building blocks of proteins. They contain an amino group (-NH2) and a carboxylic acid group (-COOH) attached to the same carbon atom, known as the alpha carbon. In the video, amino acids are the central focus, as they undergo various chemical reactions due to the functional groups present in their structure.

💡Alpha Carbon

The alpha carbon is the central carbon atom in an amino acid to which both the amino group and the carboxylic acid group are attached. It is a key structural component of amino acids and plays a crucial role in peptide bond formation, as discussed in the video.

💡Chemical Reactions

The video discusses various chemical reactions that amino acids can undergo, primarily due to the reactivity of their amino and carboxylic acid groups. These reactions are essential for understanding the functional properties of amino acids in biochemistry.

💡Acetylation

Acetylation is a chemical process where an acetyl group is added to a molecule. In the context of the video, amino acids can be acetylated when dissolved in cold alkali and then treated with acetic anhydride, resulting in the formation of an acetylated amino acid.

💡Benzoate

Benzoate refers to benzoic acid or its derivatives. In the video, benzoate is mentioned in the context of a detoxification process where glycine reacts with benzoic acid to form hippuric acid, aiding in the neutralization of a toxic molecule.

💡Methylation

Methylation is the addition of a methyl group (-CH3) to a molecule. The video describes how amino acids can undergo methylation when treated with methyl iodide in an alkaline environment, resulting in the formation of a betaine of the amino acid.

💡Sanger's Reagent

Sanger's reagent, also known as 1-fluoro-2,4-dinitrobenzene (FDNB), is used in the video to illustrate a color reaction with amino acids. When FDNB condenses with the free amino group of an amino acid under alkaline conditions, it forms a yellow-colored product known as DNP amino acid, which is useful for identifying amino acids.

💡Nitrous Acid (HNO2)

Nitrous acid is used in the video to demonstrate its reaction with the free amino group of an amino acid, resulting in the formation of a hydroxyl acid and the release of nitrogen gas and water. This reaction is significant for estimating free amino groups in amino acids, peptides, or proteins.

💡Oxidative Deamination

Oxidative deamination is a biochemical process where an amino acid is converted to a keto acid and ammonia through the action of oxidative enzyme systems, particularly in the liver and kidneys. The video explains this reaction as a two-step process involving the formation of an imino acid intermediate.

💡Formaldehyde

In the video, formaldehyde is mentioned in the context of its reaction with the amino group of an amino acid. This reaction proceeds with the addition of formaldehyde and subsequent titration with alkali until two molecules of formaldehyde have reacted, leading to the formation of a dimethylol amino acid.

💡Schiff Base

A Schiff base is a compound with a C=N bond formed from the reaction between an amine and an aldehyde. The video describes the formation of a Schiff base when an amino acid reacts with an aromatic aldehyde like benzaldehyde in the presence of an alkali, resulting in a condensation reaction and the subsequent loss of a water molecule.

💡Ninhydrin

Ninhydrin is a chemical reagent used in the video to illustrate a color reaction with amino acids. When ninhydrin reacts with an amino acid, it forms a purple-colored compound known as Ruheim's purple or dico hydride Aladin, which is used to detect the presence of amino acids.

💡Carbon Dioxide

In the video, the reaction of amino acids with carbon dioxide is described as a condensation reaction that results in the formation of an N-carboxy amino acid. This simple reaction is an example of how amino acids can interact with other molecules in biochemical processes.

💡Veratryl Reaction

The Veratryl reaction, as mentioned in the video, involves the reaction of copper ions with the unshared electron pair of nitrogen in a compound containing two NH2 groups. This reaction results in the formation of a violet-colored complex, which is categorized as a color reaction of amino acids.

Highlights

Amino acids are organic biomolecules with two oppositely charged functional groups attached to the same carbon atom, known as the alpha carbon.

Amino acids participate in various chemical reactions, including those involving the amino group, carboxylic group, or both.

This video focuses on reactions of amino acids that occur purely due to the involvement of the amino group.

Isolation of an amino acid is achieved by dissolving it in cold alkali and adding acetic anhydride.

Benzoate conjugation is a detoxification process in the body where glycine reacts with benzoic acid to form hippuric acid.

Methylation of amino acids involves treatment with methyl iodide or dimethyl sulfate in an alkaline environment, resulting in betaine formation.

Sanger's reagent (1-fluoro-2,4-dinitrobenzene, FDNB) reacts with the free amino group of amino acids under alkaline conditions to form DNP amino acids, which are bright yellow.

Nitrous acid (HNO2) reacts with the free amino group of amino acids, resulting in the formation of hydroxyl acids and the release of nitrogen gas and water.

Oxidative deamination is a two-step reaction where amino acids are converted to keto acids and ammonia by oxidative enzyme systems in tissues like liver and kidney.

Reaction with formaldehyde involves the addition of formaldehyde to the amino group, leading to the formation of dimethyl all amino acids.

Aromatic aldehydes react with amino acids in the presence of alkali to form Schiff bases, which are unstable and lose water to form a C=N double bond.

Ninhydrin reacts with amino acids to form a purple-colored complex known as Ruhemann's purple, which is a color reaction of amino acids.

Amino acids react with carbon dioxide in a condensation reaction to form N-carboxy amino acids.

The Verret reaction involves the reaction of copper ions with the unshared electron pair of nitrogen in amino acids, forming a violet-colored complex.

The video provides a comprehensive overview of the reactions of amino acids, including their mechanisms and practical applications.

Links to previous videos on amino acid structure and properties are provided in the description for further information.

The video is prepared by Dr. Dheeraj K. Goswami, offering expert insights into amino acid reactions.