Synthetase Vs Synthase


The terms ‘synthetase’ and ‘synthase’ sound similar and often get confused with one another. However, both have entirely different functions and play a vital role in various biochemical processes that take place in living organisms.

In this article, we will define, compare, and contrast these terms, their roles and importance, and the difference between them. Let’s start with understanding these terms:

What is Synthetase?

A synthetase refers to an enzyme that involves the transfer of a functional group(s) from a donor molecule to an acceptor molecule in a process called ligation. The donor molecule, which is usually a nucleotide coenzyme carrying energy (such as ATP), is coupled with an acceptor molecule to generate a high-energy intermediate. This intermediate is then used to fuel the reaction to make required biomolecules.

The synthetase enzyme works by combining two different molecules, thereby making new chemical bonds between them. This process is found to occur in various metabolic pathways such as amino acid synthesis, lipid synthesis, and nucleic acid synthesis.

What is Synthase?

A synthase, on the other hand, is also an enzyme that catalyzes the formation of a new chemical bond between two molecules but does not require energy coupling. Instead, this enzyme directly catalyzes the joining of two parts of a molecule with the help of a specific chemical reaction.

This enzyme can also be called a lyase, as it uses its energy to cleave a chemical bond and form a new one. In comparison to synthetase, fewer metabolic pathways have been found that involve synthases; still, they play a crucial role in many biochemical reactions essential for the proper functioning of the metabolic pathways.

Comparing and Contrasting Synthetase and Synthase

The critical difference between these two enzymes lies in the way they catalyze the chemical reaction between two molecules. It is important to note that both enzymes perform similar functions, which is to form new chemical bonds. However, their mechanisms of action and the type of chemical reaction that they catalyze are different.

The synthetases use high-energy intermediates to couple a donor molecule with an acceptor molecule to form a new chemical bond. The intermediates, like ATP, are hydrolyzed during the process, which can provide energy for the transfer of groups, and this energy can be used to fuel the reaction further.

Meanwhile, synthases, as discussed, do not require an energy input and do not produce high-energy intermediates. They are capable of catalyzing the reaction between two substrates that can bond or break themselves without the need for an energy transfer. The only energy consumed is for the cleavage or addition of a substrate.

FAQs about Synthetase and Synthase

Q. What are the examples of synthetases?
A. Some examples of synthetases include amino acid synthetases (for making amino acids), acetyl-CoA synthetase (for lipid synthesis), and DNA ligase (for DNA synthesis).

Q. What are the examples of synthases?
A. Some of the examples of synthases include fatty acid synthase (for fatty acid synthesis) and ribosome synthase (for making ribosomes).

Q. How do these enzymes contribute to our metabolism?
A. Both these enzymes play an essential role in metabolism by allowing the formation of new biomolecules from simple precursors. These are vital reactions that occur within our bodies and require the proper functioning of these enzymes.

Q. Can these enzymes be inhibited or enhanced to treat metabolic diseases?
A. Yes, these enzymes can be manipulated to treat metabolic diseases. The targeted inhibition or enhancement of these enzymes can slow down or accelerate the rate of the biochemical reaction, depending on the specific condition.

Q. Are these enzymes found only in humans or are they widespread in other organisms?
A. These enzymes are found in various organisms, including plants, animals, and microorganisms, and play an essential role in their metabolism.


The terms synthetase and synthase may sound similar, but they have different roles in biochemical reactions. Their comparison and contrasting suggest that each enzyme behaves differently from the other, and they play a vital role in different metabolic pathways.

While synthetases need energy transfer to generate a high-energy intermediate and then bond two substrates, synthases don’t require energy to catalyze the reaction. However, both these enzymes contribute to the sustained biochemical reaction that allows the body to synthesize biomolecules and help maintain the proper functioning of the body.