Difference Between Ligase and Lyase

Key Difference – Ligase vs Lyase
 

The key difference between ligase and lyase is that ligases involve in the formation of chemical bonds whereas lyases cause break down of chemical bonds.

Ligases and lyases are enzymes. Enzymes are macromolecular compounds that can act as biological catalysts. These compounds can increase the reaction rate of a certain chemical reaction by reducing the activation energy barrier. Ligases are a type of enzymes that bring about ligation of DNA or another substance. Therefore, ligases cause bond formations between different components. Lyases are enzymes that cause break down of chemical bonds other than hydrolysis and oxidation.

CONTENTS

1. Overview and Key Difference
2. What is Ligase
3. What is Lyase
4. Side by Side Comparison – Ligase vs Lyase in Tabular Form
5. Summary

What is Ligase?

Ligase is an enzyme that brings about ligation of DNA or another substance. This means ligases catalyzes the joining of two components. This joining of two components results in the formation of a new chemical bond. Ligases are also known as synthetases because these enzymes cause the formation of new compounds.

Ligases cause the formation of larger molecules than the starting compounds. Hydrolysis takes place during the action of the ligase. There are about 50 different ligases. These ligases require energy provided by ATP (Adenosine triphosphate). When the ligase has used the energy from ATP, the ATP is converted into ADP (Adenosine diphosphate).

A common example of this class is DNA ligase. This enzyme is used to cover the openings present in a DNA strand. DNA ligases can join complementary strands during the DNA replication. Due to this reason, ligases are also known as a molecular glue.

What is Lyase?

Lyases are a group of enzymes that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure. This means lyases catalyze the cleavage of certain chemical bonds.

These bond cleavages occur in the form of eliminations that results in an unsaturated product (a compound having double bonds). However, hydrolysis or oxidations dos not occur in this catalysis. Lyases act on a single reactant giving two different products; one product is the unsaturated compound, and the other product is the eliminated component.

Some of the chemical reactions catalyzed by lyases are reversible whereas most other reactions are irreversible. But for the reverse reaction to occur, lyases require two reactants; unsaturated compound and the small molecules that are going to the substituted to the double bond.

Many reactions in the glycolysis and Krebs cycle in our body are catalyzed by lyases. Ex: Cleavage of fructose 1,6-bisphosphate (F 1,6-BP) forms two compounds named as glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP). This reaction is given in the above image.

What is the Difference Between Ligase and Lyase?

Summary – Ligase vs Lyase

Lyases and ligases are forms of enzymes. These are found mainly in biological systems as biological catalysts. The difference between ligase and lyase is that ligases break down chemical bonds whereas lyases involve in the formation of chemical bonds.

Reference:

1.Britannica, The Editors of Encyclopaedia. “Ligase.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 12 Aug. 2010. Available here 
2.“Lyase.” Wikipedia, Wikimedia Foundation, 25 Mar. 2018. Available here 
3.“Ligase.” Wikipedia, Wikimedia Foundation, 25 Mar. 2018. Available here

Image Courtesy:

1.’DNA Ligase schema’By Swts0litude at English Wikibooks, (CC BY-SA 3.0) via Commons Wikimedia  
2.’Lyasesexample’By Melowdeeh at English Wikibooks (Public Domain) via Commons Wikimedia