Problem 132 - A Complete Resource Book in Chemistry for JEE Main

Question

The characteristics of glycosidic linkage is/ are (a) ether linkage of sugar (b) it is hydrolysed by acid (c) it is hydrolysed by alkali (d) it is also hydrolysed by specific enzyme

Step-by-Step Solution

Answer

The characteristics of glycosidic linkage are: (a) ether linkage of sugar, (b) hydrolyzed by acid, (d) hydrolyzed by specific enzyme.

Step 1: Definition of Glycosidic Linkage

A glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may be another carbohydrate. It involves the linkage of two sugar molecules through an oxygen atom, thus forming an ether linkage.

Step 2: Understanding Ether Linkage

An ether linkage is a bond between two oxygen atoms to an alkyl or aryl group. In the case of glycosidic bonds, it connects the anomeric carbon of one sugar to an oxygen on another sugar, creating an ether-like structure.

Step 3: Hydrolysis by Acid

Glycosidic bonds can be broken down by hydrolysis with the use of an acid. This means that under acidic conditions, water can add across the bond, breaking it and releasing the individual sugar units.

Step 4: Hydrolysis by Specific Enzymes

Specific enzymes called glycosidases or glucosidases can catalyze the hydrolysis of glycosidic linkage. These enzymes are highly specific for the sugar it acts on and effectively break down glycosidic bonds.

Step 5: Conclusion based on Characteristics

Given the characteristics and behaviors analyzed, glycosidic linkages exhibit ether linkages of sugars, can be hydrolyzed by acid, and are also hydrolyzed by specific enzymes. Alkali typically do not hydrolyze glycosidic linkages under normal conditions.

Key Concepts

Covalent Bond in Carbohydrates

Glycosidic linkages are essential in things like polysaccharides, where sugars link together. At its core, a glycosidic linkage is a covalent bond. This means it's a strong bond, holding atoms together firmly within the molecule.

Covalent bonds in carbohydrates primarily involve the joining of two sugar molecules through an oxygen atom. The bond is formed between the anomeric carbon of one sugar and the oxygen of another sugar molecule, essentially bridging the two sugars into a larger structure. This type of bond not only creates complex carbohydrates, such as starches and cellulose, but it also plays a significant role in the function and stability of these molecules within biological systems.

Understanding these bonds helps to grasp how sugars link to form diverse structures and perform a wide range of biological functions.

Ether Linkage

The hallmark of glycosidic linkage is its ether character. In chemical terms, an ether linkage is a connection of two hydrocarbons through an oxygen atom.

In glycosidic bonds, this type of linkage connects the anomeric carbon atom of one sugar to the oxygen atom of another sugar, resembling an ether's bridge-like connection.

• This ether-like linkage contributes to the glycosidic bond's stability under certain conditions.
• Ether linkages in sugars allow for the creation of complex carbohydrates, enhancing their ability to store energy efficiently.

Understanding this ether characteristic helps explain why these bonds are relatively stable and less reactive under basic conditions.

Hydrolysis by Acids and Enzymes

Breaking down glycosidic bonds can be achieved through hydrolysis, a process that involves adding water to split the bond. While stable in basic environments, acids and specific enzymes can target these bonds effectively.

**Hydrolysis by Acids**

• Under acidic conditions, the addition of water isn't enough; the acid acts as a catalyst to speed up the reaction.
• This process results in splitting the linked sugars back into individual units, which is crucial in digestive processes.

**Hydrolysis by Specific Enzymes**
Specialized enzymes, like glycosidases, can break glycosidic bonds.

• These enzymes are highly specific, meaning each enzyme typically catalyzes the hydrolysis of specific sugar bonds.
• Enzymatic hydrolysis is a crucial biological process that allows organisms to efficiently break down carbohydrates for energy.

A thorough understanding of these methods of hydrolysis is critical in biochemistry, as they illustrate how complex carbohydrates are metabolized.