C-terminus

Definition

The C-terminus, or carboxy-terminus, refers to the end of a polypeptide or protein chain where the carbon atom of the carboxyl (COOH) group is located. It is one of the defining structural features of peptides and proteins, and its properties play a crucial role in their function and behavior.

5 Must Know Facts For Your Next Test

1. The C-terminus is the end of a polypeptide chain where the carboxyl (COOH) group is located, in contrast to the N-terminus where the amino (NH2) group is found.
2. The C-terminus plays a crucial role in determining the overall structure and function of a protein, as it can participate in various interactions and modifications.
3. The charge and reactivity of the C-terminus can influence the solubility, stability, and interactions of a protein within the cellular environment.
4. Many post-translational modifications, such as the addition of functional groups or the removal of the terminal amino acid, occur at the C-terminus and can alter the protein's properties.
5. The C-terminus is often used as a reference point for protein sequencing and structural analysis, as it provides a consistent and well-defined endpoint for the polypeptide chain.

Review Questions

• Explain the significance of the C-terminus in the structure and function of peptides and proteins.
  • The C-terminus is a crucial structural feature of peptides and proteins, as it represents the end of the polypeptide chain where the carboxyl (COOH) group is located. The properties of the C-terminus, such as its charge, reactivity, and potential for post-translational modifications, can influence the overall structure, stability, and function of the protein. For example, the C-terminus can participate in intramolecular and intermolecular interactions that contribute to protein folding and the formation of higher-order structures. Additionally, modifications at the C-terminus can alter the protein's solubility, stability, and interactions with other biomolecules, thereby affecting its biological activity.
• Compare and contrast the roles of the C-terminus and N-terminus in peptide and protein structure and function.
  • The C-terminus and N-terminus of a polypeptide or protein chain play distinct yet complementary roles in determining the overall structure and function of the biomolecule. While the N-terminus represents the start of the chain where the amino (NH2) group is located, the C-terminus is the end of the chain where the carboxyl (COOH) group is found. The N-terminus is often involved in initiating protein folding and can participate in specific interactions, such as binding to other proteins or enzymes. In contrast, the C-terminus can influence the solubility, stability, and post-translational modifications of the protein, which can alter its function and behavior within the cellular environment. Together, the N-terminus and C-terminus work in concert to define the primary structure, secondary structure, and higher-order conformations of peptides and proteins, ultimately shaping their biological activities.
• Discuss how the properties of the C-terminus can be exploited for the purification, characterization, and applications of peptides and proteins.
  • The unique properties of the C-terminus can be leveraged for various applications in the study and utilization of peptides and proteins. For example, the distinct charge and reactivity of the C-terminus can be used for the purification of proteins through techniques like ion-exchange chromatography or affinity-based methods, where the C-terminus is targeted by specific ligands or antibodies. Additionally, the C-terminus can serve as a reference point for protein sequencing and structural analysis, as it provides a well-defined endpoint for the polypeptide chain. Furthermore, the ability to modify the C-terminus through post-translational processes or engineered techniques can be exploited to alter the solubility, stability, and functionality of proteins, enabling the development of novel therapeutic agents, biosensors, or biocatalysts. By understanding and manipulating the properties of the C-terminus, researchers and biotechnologists can expand the potential applications of peptides and proteins in various fields, from medicine and biotechnology to materials science and nanotechnology.

Related terms

N-terminus: The N-terminus, or amino-terminus, is the opposite end of a polypeptide or protein chain where the nitrogen atom of the amino (NH2) group is located.

Peptide Bond: The covalent bond formed between the carboxyl group of one amino acid and the amino group of another, which links the amino acids together to form a polypeptide chain.

Protein Folding: The process by which a protein structure assumes its functional 3D shape from its primary amino acid sequence, which is determined by the arrangement and interactions of the C-terminus and N-terminus.