The key difference between alpha and beta oxidation is that alpha oxidation mainly takes place in the brain and liver where one carbon atom is lost in the form of a carbon dioxide molecule, whereas beta oxidation process mainly takes place in the mitochondria matrix where two-carbon units are released as acetyl CoA per cycle.
Alpha oxidation is a technique in which certain fatty acids undergo breakdown by the removal of a single carbon from the carboxyl end of the molecule. Beta oxidation is a catabolic process in which fatty acid molecules are broken down inside the cytosol of prokaryotes and in the mitochondria in eukaryotes, generating acetyl CoA, NADH, and FADH2.
CONTENTS
1. Overview and Key Difference
2. What is Alpha Oxidation
3. What is Beta Oxidation
4. Alpha vs Beta Oxidation in Tabular Form
5. Summary – Alpha vs Beta Oxidation
What is Alpha Oxidation?
Alpha oxidation is a technique in which certain fatty acids undergo breakdown by the removal of a single carbon from the carboxyl end of the molecule. This can take place in humans as it is useful in peroxisomes for the breakdown of dietary phytanic acid that is unable to undergo beta oxidation (this is because of the beta-methyl branch in this molecule) into pristanic acid. Thereafter, the pristanic acid can acquire acetyl-CoA, which subsequently turn into a beta-oxidzed product yielding propionyl-CoA.
Figure 01: Alpha Oxidation Process with Enzymatic Steps
It is considered that alpha-oxidation takes place entirely within peroxisomes. There are four major steps in this process. First, the phytanic acid gets attached to CoA, forming phytanoyl CoA. Next, phytanoyl CoA undergoes oxidation through phytanoyl CoA dioxygenase with the use of ferrous ions and oxygen gas. This step yields 2-hydroxyphytanoyl-CoA. In the third step, 2-hydroxyphytanoyl-CoA cleave into pristanal and formyl CoA by 2-hydroxyphytanoyl-CoA lyase in a TPP-dependent reaction. Finally, as the fourth step, pristanal undergoes oxidation by aldehyde dehydrogenase, forming pristanic acid.
What is Beta Oxidation?
Beta oxidation is a catabolic process in which fatty acid molecules are broken down inside the cytosol of prokaryotes and in the mitochondria in eukaryotes generating acetyl CoA, NADH, and FADH2. This acetyl CoA will enter the citric acid cycle. The NADH and FADH2 produced here act as co-enzymes that are useful in the electron transport chain.
Figure 02: Mitochondrial Fatty Acid Beta Oxidation Process
Beta oxidation is named as such because of the beta carbon of the fatty acid that undergoes oxidation to make a carbonyl group. Moreover, this process is primarily facilitated by the mitochondrial trifunctional protein (it is an enzyme that is associated with the inner mitochondrial membrane).
What is the Difference Between Alpha and Beta Oxidation?
Alpha oxidation is a technique in which certain fatty acids undergo breakdown by the removal of a single carbon from the carboxyl end of the molecule. Beta oxidation is a catabolic process in which fatty acid molecules are broken down inside the cytosol of prokaryotes and in the mitochondria in eukaryotes generating acetyl CoA, NADH, and FADH2. The key difference between alpha and beta oxidation is that alpha oxidation mainly takes place in the brain and liver where one carbon atom is lost in the form of a carbon dioxide molecule, whereas beta oxidation process mainly takes place in the mitochondria matrix where two-carbon units are released as acetyl CoA per cycle.
Below is a summary of the difference between alpha and beta oxidation in tabular form for side by side comparison.
Summary – Alpha vs Beta Oxidation
Alpha and beta oxidation are important biochemical processes. The key difference between alpha and beta oxidation is that alpha oxidation mainly takes place in the brain and liver, where one carbon atom is lost in the form of a carbon dioxide molecule, whereas beta oxidation mainly takes place in the mitochondria matrix where two-carbon units are released as acetyl CoA per cycle.
Reference:
BSC Chemistry – igntu.ac.in. (n.d.). Retrieved March 23, 2022, from http://www.igntu.ac.in/eContent/IGNTU-eContent-726123491088-BBA-2-Dr.RahilYusufZai-BusinessEnvironment-4.pdf
Image Courtesy:
1. “Alpha oxidation” By SlothMcCarty – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “LCHAD deficiency” By User:Innerstream – Own work, modeled after File:LCHAD deficiency.jpg (Public Domain) via Commons Wikimedia