Ligase n., plural: ligases <ˈlaɪɡeɪz> Definition: enzyme that catalyzes the binding of 2 molecules

An enzyme is a catalyst or a chemical developed by cell to speed up a biochemical reaction. The is normally a protein molecule with a characteristic sequence of amino acids that fold to develop a three-dimensional structure, which offers the molecule its distinct properties. One more molecule through catalytic task is ribozyme, one enzyme make of RNA rather than protein. Enzymes might be classified and named according to the reaction lock catalyze: (1) oxidoreductases, (2) transferases, (3) lyases, (4) isomerases, and (6) ligases. In essence, ligases room a team of enzymes that catalyze the binding of two molecules.

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Ligase Definition

What is ligase? words ‘ligase‘ come from the Latin word ‘ligare‘, which method “to bind”. In biology, ligase is a class of enzyme. But, what does ligase do? permit us define ligase.

Ligase is the class of enzyme that brings around the binding or joining of two molecules. The is, by an interpretation in biology, the class of enzyme the catalyzes the binding or joining of two macromolecules by forming brand-new bonds prefer C-O, C-N, and also C-S. Ligase enzyme catalyzes the ligase reaction for, e.g.

A-D + X A-X + d OR B-C + V-W B-V + c + w + f + g

Wherein d, c, w, f, g represent little pendant groups that have been hydrolyzed during the procedure of ligation or involvement of 2 macromolecules (e.g. A-X and B-V, in the above reactions).

About 50 ligase enzymes room known and also are regularly referred to as “molecular glue”. DNA ligase is one example. The catalyzes the DNA fragments’ binding by developing a phosphodiester bond between complementary ends of the DNA fragments. Thus, DNA ligase plays a an essential role in repairing, replicating, and also recombination the DNA. Let us recognize the ligase mechanism with the assist of DNA Ligase as an example.

Biology/Biochemistry definition: Ligase is one enzyme the catalyzes the binding of two molecules. An example is a DNA ligase that links two fragments of DNA by creating a phosphodiester bond. Ligases are classified right into six subclasses: (1) EC 6.1 (ligases developing carbon-oxygen bonds), (2) EC 6.2 (ligases forming carbon-sulfur bonds), (3) EC 6.3 (ligases creating carbon-nitrogen bonds), (4) EC 6.4 (ligases developing carbon-carbon bonds), (5) EC 6.5 (ligases developing phosphoric ester bonds), and (6) EC 6.6 (ligases forming nitrogen-metal bonds). Synonym: synthetase.

DNA Ligase

Definition: DNA ligases space the ligases that join or tie the 2 DNA fragments (also well-known as Okazaki fragments) by creating a phosphodiester bond.

Functions of DNA Ligase

DNA Ligase is essential for DNA replication as well as the DNA repairing process. DNA Ligase is widely made use of in laboratories for moving out recombinant DNA experiments. The many widely utilized ligase in a science laboratory is the DNA ligase.

READ: Ligase in genetic Engineering

Mechanism of DNA Ligase

DNA ligase binds the 3′ hydroxyl end of one nucleotide (or acceptor) through the 5′ phosphate end of an additional (donor) by two covalent phosphodiester bonds in the adhering to steps:

In the an initial step, the DNA pieces or DNA segment or Okazaki pieces are reorganized v their active sites. The lysine residue that the active site the the Ligase it s okay adenylated v the addition of AMP. The release of pyrophosphate accompanies adenylation of Ligase. Ligase move the AMP come the 5′ phosphate finish of the donor with the formation of the pyrophosphate bond. The 5′ phosphate finish of the donor is attached to the 3′ hydroxyl end of the receptor through phosphodiester bond formation.

Figure 1: DNA ligase mechanism. Credit: Sciencelearn.org.nz.

Generally, these ligases are named according come the substrate or the macromolecules affiliated in the reaction; for, e.g., amino acid–RNA ligase catalyzes, the C-O bond formation between amino acid and transfer RNA.

Ligase enzymes are synonymous v synthetase enzymes. However, synthetase enzymes space often puzzled with synthase enzymes. Historically, synthetase enzyme were defined as the “ligase that catalyzes the authorized of two macromolecules through the use of the energy molecules acquired by the hydrolysis the nucleoside triphosphates (like ATP, GTP, CTP, TTP, and UTP), because that example, hydrolysis the adenosine triphosphate (ATP) molecules to adenosine diphosphate (ADP)”.

On the various other hand, synthase enzymes room the ones the catalyze the synthetic of biological macromolecules without the hydrolysis of nucleoside triphosphates.

However, later on Joint commission on Biochemical Nomenclature (JCBN) announced that the hatchet synthetase would certainly be offered synonymously with ligase. At the very same time, ‘synthase’ would be provided for the synthesis-catalyzing enzymes that may or may not involve power utilization.

There are 6 classes that enzymes and also ligases are among them. The various other classes of enzymes incorporate oxidoreductases, transferases, hydrolases, isomerases, and also lyases. Ligase and lyase are very closely related class of enzymes. However, Ligase and also lyase are various classes of enzymes.

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Table 1: Lyase Vs Ligase Ligase Lyase
Enzymes the bring about joining or binding of two organic macromolecules Enzymes the catalyze the chemistry bond breaking in a biological molecule
Bond formation Bond cleavage
Ligase enzyme plot via a hydrolysis reaction Lyases act by reactions various other than hydrolysis and also oxidation. Lyases generally act by an remove reaction
Ligase action on 2 molecules simultaneously Lyase action on just one molecule in ~ a time
DNA replication is completed with the assist of DNA Ligase Lyases are vital part that the glycolysis and also Kreb cycle

Ligase Function

This class of enzymes plays a vital role by joining two complementary macromolecules like nucleic acid. DNA ligase enzymes bring out the repairing, replication, and also recombination that DNA. Ligases are one of the many widely used enzymes in the molecular biology laboratory. Ligases are offered in recombinant DNA cloning to tie annealed fragments of limit endonuclease.


Based top top the molecule bond catalyzed by the ligase enzyme, ligase can be classified into six subclasses (see Table 2).

Table 2: six subclasses the ligases molecule bond connected Ligase subclass example
Carbon-Oxygen bonds (C-O) EC 6.1 Aminoacyl tRNA synthetase
Carbon-Sulfur binding (C-S) EC 6.2 Succinyl coenzyme A synthetase, Thiokinase
Carbon-Nitrogen binding (C-N) EC 6.3 Ubiquitin ligase, argininosuccinate synthetase
Carbon-Carbon bonds (C-C) EC 6.4 Gamma-glutamyl carboxylase, Polyketide synthase
Phosphoric ester bonds EC 6.5 DNA ligase
Nitrogen-metal bonds EC 6.6 Chelatases

Note: EC stands for Enzyme Commission

Ligase Examples

Ubiquitin Ligases (C-N bond) Glutamate–cysteine ligase (C-N bond) Aminoacyl tRNA synthetase (C-O bond) Succinyl coenzyme A synthetase (C-S bond) Acetyl—CoA synthetase (C-S bond) Pyruvate carboxylase (C-C bond) Acetyl-CoA carboxylase (C-C bond) Propionyl-CoA carboxylase (C-C bond) Methylcrotonyl-CoA carboxylase (C-C bond) DNA ligase (Phosphoric ester bonds) Magnesium chelatase (Nitrogen-metal bonds) Cobalt chelatase (Nitrogen-metal bonds) DNA synthetase