Difference Between Oxidative and Nonoxidative Deamination

The key difference between oxidative and nonoxidative deamination is that the oxidative deamination occurs via the oxidation of amino group amino acids whereas the nonoxidative deamination occurs via reactions other than oxidation.

Deamination is, as its name describes, the removal of an amine group from any molecule. These are chemical reactions catalyzed by deaminase enzymes. In our body, this type of reactions occur in the liver and sometimes in the kidney as well (ex: deamination of glutamate in kidneys). There, the removed amine group converts into ammonia and excreted from our body. Furthermore, there are four main reactions that take place as deamination reactions; they are oxidation, reduction, hydrolysis, and intramolecular reactions. Out of these, except for oxidation, other reactions are nonoxidative reactions.

CONTENTS

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

What is Oxidative Deamination?

Oxidative deamination is the process of removal of an amine group from a molecule via oxidation. This type of reactions largely occurs in liver and kidney. It involves the generation of alpha-keto acids and some other oxidized products from amine groups. This reaction is very important in the catabolism of amino acids. It forms a catabolized product from amino acids. the byproduct of this reaction is ammonia which is a toxic byproduct. Here, the amine group converts into ammonia. And then, this ammonia converts into urea and excreted from our body.

Most of the times, glutamic acid or glutamate is the main reactant of this type of reactions. Because, glutamic acid is the end product of many transamination reactions that take place in our cells. Furthermore, the enzyme involved in this reaction is glutamate dehydrogenase. This enzyme catalyzes the transfer of an amino group to an alpha-keto acid group. Also, there is another enzyme that involves in this type of reactions. It is the monoamine oxidase enzyme that catalyzes the deamination via the addition of oxygen.

What is Nonoxidative Deamination?

Nonoxidative deamination is the process of removal of an amine group from a molecule via different reactions other than oxidation. We call it “direct deamination” without oxidation. These reactions include reduction, hydrolysis and intramolecular reactions. However, this reaction also involves the production of toxic byproduct ammonia from amino acids. Moreover, the most common amino acids that undergo this type of reactions are serine, threonine, cysteine and histidine. Similarly, the most common enzymes involved in this reaction are dehydratases, lyases and amide hydrolases.

Reduction deamination occurs via reduction of amine group into a fatty acid. Hydrolytic deamination involves the conversion of amine group into the hydroxy acid group. From the intramolecular reaction, the amine group converts into an unsaturated fatty acid group. As an example, dehydratase enzymes can convert serine into pyruvate and ammonia and also it can convert threonine into alpha-ketobutyrate and ammonia.

What is the Difference Between Oxidative and Nonoxidative Deamination?

Deamination is the removal of an amine group from a molecule. Thus, in deamination, the amine group converts into different other products depending on the type of reaction it undergoes. The key difference between oxidative and nonoxidative deamination is that the oxidative deamination occurs via the oxidation of amino group amino acids whereas the nonoxidative deamination occurs via reactions other than oxidation. Because of this difference, the chemical reactions involved in these processes are also different from each other. That is, the oxidative deamination involves oxidation while the nonoxidative deamination involves reduction, hydrolysis or intramolecular reactions. Furthermore, another significant difference between oxidative and nonoxidative deamination is in the enzymes involved in these reactions. That is, the glutamate dehydrogenase and monoamine oxidase involve in the oxidative process whereas the dehydratases, lyases, and amide hydrolases involve in the nonoxidative process as enzymes.

The below infographic outlines the difference between oxidative and nonoxidative deamination in tabular form.

Summary – Oxidative vs Nonoxidative Deamination

Deamination is the liberation of ammonia via the deamination of an amine group. There are two major types of oxidative and nonoxidative deamination. The nonoxidative deamination includes reactions other than oxidation such as reduction, hydrolysis, and intramolecular reactions. Hence, the key difference between oxidative and nonoxidative deamination is that the oxidative deamination occurs via the oxidation of amino group amino acids whereas the nonoxidative deamination occurs via reactions other than oxidation.

Reference:

1. “Oxidative Deamination.” Wikipedia, Wikimedia Foundation, 24 Apr. 2018. Available here 
2. Ahmed, Minhaz. “TRANSDEAMINATION AND DEAMINATION.” LinkedIn SlideShare, 24 Apr. 2014. Available here 

Image Courtesy:

1.”Oxidative deamination”By Tomas Drab – Own work, (Public Domain) via Commons Wikimedia  
2.”Serine” (CC BY-SA 3.0) via Commons Wikimedia