What is the Difference Between Aliphatic and Aromatic Amino Acids?

The main difference between aliphatic and aromatic amino acids lies in their chemical structures and properties.

Aliphatic Amino Acids:

• Consist of aliphatic side chain functional groups.
• Nonpolar and hydrophobic amino acids.
• Typically found within protein molecules, with two exceptions: alanine and glycine, which can be found either inside or outside of a protein molecule.
• Examples include alanine, isoleucine, leucine, proline, and valine.

Aromatic Amino Acids:

• Have cyclic structures with alternating double-bond characteristics.
• Aromatic ring linked directly to the chiral carbon.
• Examples include tyrosine, phenylalanine, and others.

In terms of acidity, aliphatic amino acids are driven more by the acidity of the central carbon than aromatics, given that they reach higher absolute values of electronic flux. However, electronegative aromatic substituents show less acidity on the chiral carbon than other activating substituents.

Comparative Table: Aliphatic vs Aromatic Amino Acids

Here is a table summarizing the differences between aliphatic and aromatic amino acids: