Difference Between Reductive Amination and Transamination

The key difference between reductive amination and transamination is that the reductive amination is the conversion of a carbonyl group into an amine group whereas the transamination is the transfer of an amine group from one molecule to another.

Amination is the process that we can use to introduce an amine group to a molecule. The reductive amination and transamination are two forms of amination processes. Therefore, these processes also involve in the introduction of an amine group to a molecule, but in different pathways; reductive amination involves the conversion of an existing group into an amine group whereas transamination involves the transferring of an amine group.

CONTENTS

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

What is Reductive Amination?

Reductive amination is a form of amination process in which we convert a carbonyl group into an amine group. We call it “reductive alkylation” as well. This process undergoes through an imine. The carbonyl groups that can involve in these reactions are aldehyde or ketone groups mainly. Moreover, it is one the most efficient ways of amination. Therefore, most industries use this process.

When considering the reaction process, first, the carbonyl group forms a hemiaminal group. Then it losses a water molecule to form the imine. This reaction step is reversible. By removing the water molecules formed during this reaction, we can shift the reaction towards the formation of the imine from ketone or aldehyde group. Then we should isolate this imine using a stable reducing agent such as sodium borohydride. We call it “indirect reductive amination”. If this imine formation and the reduction reaction occurs at the same time, we call it “direct reductive amination”. Finally, this imine intermediate converts into the amine form.

What is Transamination?

Transamination is a form of amination in which a chemical reaction occurs via transferring an amine group to a keto acid. This reaction forms a new amino acid. This is the most common pathway of deamination of amino acids. In this process, essential amino acids convert into nonessential amino acids. in biological systems, enzymes such as transaminases and aminotransferases involve in this type of reactions.

When considering the mechanism of action of this process, it occurs in two ways. As the first step, the alpha amino group of an amino acid transfers to the enzyme. This produces an α-keto acid and the aminated enzyme. The second step of the process involves the transfer of an amino group to the keto acid acceptor. This forms the final amino acid molecule. Moreover, the enzyme regenerates because it acts as the catalyst here.

What is the Difference Between Reductive Amination and Transamination?

Amination is the process of introducing an amine group to a molecule. Reductive amination and transamination are two forms of amination. However, these two processes differ from each other according to the pathway that they introduce the amine group. Therefore, the key difference between reductive amination and transamination is that the reductive amination is the conversion of a carbonyl group into an amine group whereas the transamination is the transfer of an amine group from one molecule to another. Moreover, we can also find a difference between reductive amination and transamination in the intermediates formed by the two processes. That is, the reductive amination gives an imine while transamination gives an alpha-keto acid as the intermediate.

The below infographic tabulates the difference between reductive amination and transamination.

Summary – Reductive Amination vs Transamination

Amination is very important in biochemistry as a method of introducing an amine group to a molecule. When considering the reductive amination and transamination, the difference between reductive amination and transamination is that reductive amination is the conversion of a carbonyl group into an amine group whereas transamination is the transfer of an amine group from one molecule to another.

Reference:

1. “Transamination.” Wikipedia, Wikimedia Foundation, 15 May 2018. Available here 
2. Briers, Demarcus. “Amination vs Transamination.” DBriers.com, 11 Dec. 2012. Available here  

Image Courtesy:

1.”Reductive amination acetophenone ammonia”By V8rik (CC BY-SA 3.0) via Commons Wikimedia  
2.”Transaminierung”By Alcibiades – Own work, (Public Domain) via Commons Wikimedia