Question

Why are Glu and Asp often referred to as acidic amino acids?

Short answer

Answer: Glutamic acid (Glu) and Aspartic acid (Asp) are referred to as acidic amino acids because they possess extra carboxyl groups in their side chains, which allows them to ionize and donate H+ ions, giving them acidic properties in aqueous environments.

Step-by-step solution

Understanding Amino Acids

Amino acids are the building blocks of proteins. They are organic compounds containing an amino group (-NH2), a carboxyl group (-COOH), and a side chain (R group) that is specific to each amino acid. The amino acids differ from each other based on the properties of their side chains.

Introducing Glutamic Acid (Glu) and Aspartic Acid (Asp)

Glutamic acid (Glu) and Aspartic acid (Asp) are two amino acids that have a carboxyl group (-COOH) in their side chains. This unique property differentiates them from other amino acids and gives them their acidic nature. Let's discuss each amino acid in more detail: - Glutamic acid (Glu): The side chain of Glu contains a -CH2-CH2-COOH group. - Aspartic acid (Asp): The side chain of Asp contains a -CH2-COOH group.

Ionization of Glu and Asp

When Glu and Asp are dissolved in water, they can ionize, meaning they can donate a H+ ion, gaining a negative charge. This property is due to the presence of the extra carboxyl groups in their side chains. The ionized forms of these amino acids are represented as: - Glutamic acid: Glu^- (COO^- representing the ionized carboxyl group) - Aspartic acid: Asp^- (COO^- representing the ionized carboxyl group)

Acidity of Amino Acids

An acid is a substance that can donate a hydrogen ion (H+) or a proton. Since Glu and Asp display the ability to ionize and donate a H+ ion due to their extra carboxyl groups, they exhibit acidic properties.

Conclusion

Glutamic acid (Glu) and Aspartic acid (Asp) are commonly referred to as acidic amino acids because they possess extra carboxyl groups in their side chains, which allows them to ionize and donate H+ ions, giving them acidic properties in aqueous environments.