peptide catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of peptides, compounds of 2 or more (but usually less than 100) amino acids where the alpha carboxyl group of one is bound to the alpha amino group of another. [GOC:jl]

Peptide catabolic process is a fundamental biological process that breaks down peptides into smaller units, primarily amino acids. This process is essential for various cellular functions, including:

* **Nutrient acquisition:** Peptides derived from dietary proteins or intracellular proteins are broken down into amino acids, providing cells with essential building blocks for protein synthesis, energy production, and other metabolic processes.
* **Protein turnover:** Cells constantly synthesize and degrade proteins, a process known as protein turnover. Peptide catabolism plays a crucial role in this process, allowing cells to remove damaged or misfolded proteins and recycle their amino acids.
* **Signal transduction:** Some peptides act as signaling molecules, influencing various cellular processes. Peptide catabolism can regulate the availability of these signaling peptides, thus affecting downstream cellular responses.

The peptide catabolic process involves a series of enzymatic steps, primarily catalyzed by proteases. These enzymes cleave peptide bonds, breaking down peptides into smaller fragments.

**Key steps in peptide catabolism:**

* **Hydrolysis:** This is the primary mechanism of peptide bond cleavage. Proteases use water molecules to break the peptide bond, releasing free amino acids or shorter peptides.
* **Exopeptidases:** These enzymes cleave amino acids from the ends of peptides, either from the N-terminus (aminopeptidases) or the C-terminus (carboxypeptidases).
* **Endopeptidases:** These enzymes cleave peptide bonds within the peptide chain, generating smaller peptide fragments.

The specific enzymes involved in peptide catabolism vary depending on the organism and the specific peptide being degraded. However, some common proteases include:

* **Trypsin:** Cleaves peptide bonds on the C-terminal side of lysine and arginine residues.
* **Chymotrypsin:** Cleaves peptide bonds on the C-terminal side of aromatic amino acids (phenylalanine, tyrosine, tryptophan).
* **Pepsin:** Active in the acidic environment of the stomach, cleaves peptide bonds on the N-terminal side of aromatic amino acids and leucine.
* **Cathepsins:** A family of lysosomal proteases that play a role in intracellular protein degradation.

**Regulation of peptide catabolism:**

Peptide catabolism is tightly regulated to ensure proper protein turnover, amino acid availability, and cellular signaling. This regulation involves:

* **Transcriptional control:** The expression of protease genes can be regulated by various factors, such as nutrient availability, cellular stress, and hormonal signals.
* **Post-translational modifications:** Proteases can be activated or inhibited by post-translational modifications, such as phosphorylation or ubiquitination.
* **Substrate specificity:** Different proteases have specific substrate preferences, allowing for targeted protein degradation.

**Disorders of peptide catabolism:**

Defects in peptide catabolism can lead to various disorders, including:

* **Amino acid metabolism disorders:** These disorders arise from deficiencies in specific enzymes involved in amino acid breakdown, leading to the accumulation of toxic metabolites.
* **Protein misfolding diseases:** Errors in protein folding can lead to the accumulation of misfolded proteins, which can overwhelm the proteolytic machinery and cause cellular damage.

Overall, peptide catabolic process is a critical biological process that ensures proper protein turnover, nutrient acquisition, and cellular signaling. Dysregulation of this process can lead to various diseases, highlighting the importance of understanding the underlying mechanisms involved.'"

Proteins (9)

Compounds (156)