Key Difference – Glycosidic Bond vs Peptide Bond
Glycosidic bonds and peptide bonds are two types of covalent bonds which can be found in living systems. The formation of both of these bonds involves the removal of a water molecule and this process is called dehydration reactions (also known as condensation reactions). But, these two bonds are very different from each other. The key difference between glycosidic bond and peptide bond is in the way they are formed; glycosidic bonds are found in sugar molecules and peptide bonds are formed between two amino acids.
What is Glycosidic Bond?
A glycosidic bond is a covalent bond which links a carbohydrate (sugar) molecule to another group; it can be another carbohydrate group or any other group. This bond is formed between two functional groups; a hemiacetal or hemiketal group of an asaccaharide or a molecule derived from a saccharide with a hydroxyl group of another molecule such as an alcohol. Aglycoside is a substance containing a glycosidic bond.
Glycosidic bonds play a very special role in the existence of living organisms on the earth since they are important for the structure of all substances.
What is Peptide Bond?
A peptide bond is also known as amide bond which is formed between two amino acid molecules. An amino acid contains two functional groups; a carboxylic acid group and an amino group. The peptide bond is formed between an amino group of one amino acid and a carboxylic acid of the other amino acid. This reaction removes a water molecule (H2O) and hence it is called dehydration synthesis reaction or a condensation reaction. The resulting linkage between two amino acid molecules is called a covalent bond. These bonds are formed in living systems and the formation of a peptide bond consumes energy which is derived from ATP.
What is the difference between Glycosidic Bond and Peptide Bond?
Occurrence:
Glycosidic bond: Glycosidic bonds can be found in the sugar which we eat, trunks of trees, the hard exoskeleton of lobsters, and also in the DNA of our body.
Peptide bond: In general, peptide bonds are found in proteins and nucleic acids, DNA, and hair.
Process:
Glycosidic bond: A glycosidic bond is formed by a condensation reaction which involves the removal of a water molecule during the formation process. In contrast, the reverse reaction or the breakage of a glycosidic bond is a hydrolysis reaction; one water molecule is used in this reaction.
The formation of a glycosidic bond occurs when an alcohol group (-OH) from a molecule react with the anomeric carbon of a sugar molecule. An anomeric carbon is the central carbon atom of a hemiacetal which has single bonds to two oxygen atoms. One oxygen atom is bonded to the sugar ring and the other one is from the –OH group.
Figure 1: Glycosidic Bond
Peptide bond:
A peptide bond is formed between two amino acids. This happens when the carboxylic group of one amino acid is reacted with the amino group of another amino acid. A water molecule is removed during this process so that it is called a dehydration reaction.
Figure 2: The formation of a peptide bond between two amino acids
Definitions:
ATP: Adenosine triphosphate (ATP) is considered to be the energy currency of life. It is the high-energy molecule that stores the energy we need to do just about everything we do.
References:. (2016). Reference Terms. Retrieved 12 April, 2016, from here. (2016). Peptides & Proteins. Retrieved 12 April, 2016, from here. (2013). Glycosidic Bond: Definition & Formation. Retrieved 12 April, 2016, from here