The key difference between alpha and beta amino acid is that alpha amino acids have a carboxylic acid group and an amine group on the adjacent carbon atoms, whereas in beta amino acids the amine group is attached to the secondary carbon atom from the carboxylic acid group.
Alpha and beta amino acids are two forms of amino acids. An amino acid is an organic molecule, and it is the building block of proteins. Therefore, alpha and beta amino acid molecules act as the repeating units of proteins.
CONTENTS
1. Overview and Key Difference
2. What are Amino Acids
3. What are Alpha Amino Acids
4. What are Beta Amino Acids
5. Alpha vs Beta Amino Acid in Tabular Form
6. Summary – Alpha vs Beta Amino Acid
What are Amino Acids?
An amino acid is an organic molecule, and it is the building block of proteins. An amino acid essentially contains an amine group (-NH2), carboxylic group (-COOH), alkyl group (-R), and a hydrogen atom (-H) attached to the same central carbon atom. Therefore, the chemical elements in an amino acid are carbon, hydrogen, oxygen, and nitrogen. Sometimes, there is sulfur as well.
If the amine group and carboxylic group of the amino acid are attached to the first carbon atom of the carbon chain, we call it an alpha amino acid. Often, the term amino acid refers to alpha amino acids since they are abundant. There are 22 amino acids involved in protein formation. We call them “proteinogenic amino acids.”
What are Alpha Amino Acids?
Alpha amino acids are building blocks of proteins, and these molecules have their carboxylic acid groups and amine groups on adjacent carbon atoms. We can identify 20 naturally occurring alpha amino acids that are useful for cells in order to synthesize. We can divide these 20 amino acids into sub-categories according to the alkyl chain in the amino acid molecule. These categories include nonpolar side chains, polar side chains, acidic side chains, and basic side chains in alpha amino acids.
Figure 01: Alpha Amino Acids
Examples of alpha amino acids containing nonpolar side chains include glycine, alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, and tryptophan. Examples for alpha amino acids with polar side chains include asparagine, glutamine, serine, threonine, tyrosine, and cysteine. These amino acids usually involve in hydrogen bonding. Examples for alpha amino acids with acidic side chains include aspartic acid and glutamic acid, while examples for alpha amino acids with basic side chains include lysine, arginine, and histidine. These amino acids usually occur in the active site of enzymes and involve in hydrogen bonding and in acid/base reactivity.
What are Beta Amino Acids?
Beta amino acids are building blocks of proteins, and these molecules have carboxylic acid groups and amine groups on secondary carbon atoms.
Figure 02: Beta Amino Acid
In other words, the beta amino acid has its amine group separated from the carboxylic acid group through a carbon atom, unlike in alpha amino acids where the two functional groups are on the adjacent carbon atoms. This secondary carbon atom is also named as beta carbon, leading it to be named as beta amino acid.
What is the Difference Between Alpha and Beta Amino Acid?
Amino acids are the building blocks of proteins. There are two major types as alpha amino acids and beta amino acids and alpha amino acids are the most common forms. The key difference between alpha and beta amino acid is that alpha amino acids have carboxylic acid groups and amine groups on the adjacent carbon atoms whereas in beta amino acids the amine group is attached to the secondary carbon atom from the carboxylic acid group.
The following infographic tabulates the differences between alpha and beta amino acid.
Summary – Alpha vs Beta Amino Acid
Amino acids are the building blocks of proteins. There are two major types as alpha amino acids and beta amino acids. The key difference between alpha and beta amino acid is that alpha amino acids have carboxylic acid groups and amine groups on the adjacent carbon atoms, whereas in beta amino acids the amine group is attached to the secondary carbon atom from the carboxylic acid group. Furthermore, alpha-amino acids are the most common form.
Reference:
1. “Beta Amino Acid.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Alpha-amino-acid-general-2D” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “Beta-Amino Acid Formula V3” By Jü – Own work (CC BY-SA 4.0) via Commons Wikimedia