C-terminal amino acid

Definition

The C-terminal amino acid refers to the last amino acid residue at the carboxyl (C) terminus of a polypeptide or protein chain. This amino acid is critical in determining the overall structure and function of the protein, as it can influence the folding, stability, and interactions of the biomolecule.

5 Must Know Facts For Your Next Test

1. The C-terminal amino acid is the last amino acid residue in a polypeptide chain and is crucial for the overall structure and function of the protein.
2. The C-terminal amino acid can influence the folding, stability, and interactions of the protein, as it is often involved in intramolecular and intermolecular interactions.
3. The C-terminal amino acid is typically the most exposed and accessible region of a protein, making it an important target for various chemical modifications and interactions.
4. In the Edman degradation method, the C-terminal amino acid is the last residue to be identified, as the process sequentially removes and identifies the N-terminal amino acids.
5. Determining the C-terminal amino acid sequence is essential for understanding the primary structure and potential post-translational modifications of a protein.

Review Questions

• Explain the role of the C-terminal amino acid in the structure and function of a polypeptide or protein.
  • The C-terminal amino acid is the last amino acid residue in a polypeptide chain and plays a crucial role in determining the overall structure and function of the protein. This terminal residue can influence the folding, stability, and interactions of the protein through intramolecular and intermolecular interactions. The C-terminal amino acid is often the most exposed and accessible region of the protein, making it an important target for various chemical modifications and interactions that can affect the protein's activity, localization, and interactions with other biomolecules.
• Describe how the C-terminal amino acid is identified during the Edman degradation method of peptide sequencing.
  • In the Edman degradation method, the C-terminal amino acid is the last residue to be identified, as the process sequentially removes and identifies the N-terminal amino acids. The Edman degradation involves the stepwise removal and identification of the N-terminal amino acid residues, working from the N-terminus towards the C-terminus of the polypeptide chain. By the time the final N-terminal amino acid is identified, the C-terminal amino acid can be deduced, as it is the only remaining residue in the chain. Determining the C-terminal amino acid sequence is essential for understanding the primary structure and potential post-translational modifications of the protein.
• Analyze the importance of the C-terminal amino acid in the context of protein structure, function, and post-translational modifications.
  • The C-terminal amino acid is a critical feature of a polypeptide or protein, as it can significantly impact the overall structure, function, and post-translational modifications of the biomolecule. The terminal residue can influence the folding and stability of the protein through intramolecular interactions, and it can also mediate important intermolecular interactions that are essential for the protein's biological activities. Additionally, the C-terminus is often a target for various post-translational modifications, such as the addition of chemical groups or the removal of the terminal amino acid, which can alter the protein's properties, localization, and interactions with other molecules. Consequently, the identification and characterization of the C-terminal amino acid sequence are crucial for understanding the structure-function relationships of proteins and their potential roles in biological processes.

Related terms

N-terminal amino acid:

The N-terminal amino acid is the first amino acid residue at the amino (N) terminus of a polypeptide or protein chain, in contrast to the C-terminal amino acid.

Peptide bond:

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another amino acid, which links the amino acids together in a polypeptide chain.

Edman degradation:

A chemical sequencing method used to determine the amino acid sequence of a polypeptide by sequentially removing and identifying the N-terminal amino acid residue.