Peptides are short chains of amino acids linked by peptide bonds. Typically peptides contain less than 50 amino acids. Anything longer is generally referred to as a protein. Peptides play numerous important roles in the human body.
Some key facts about peptides:
- Peptides are assembled as chains of amino acids. There are 20 different amino acids that serve as the building blocks of all proteins and peptides.
- Peptides can come in many forms, from smaller peptides like dipeptides and tripeptides to larger ones like pentapeptides.
- Peptides have many functions beyond being building blocks of larger proteins. They work as hormones like oxytocin and insulin that regulate various body processes.
- Other peptides help transport complexes, regulate metabolism, or fight pathogens as part of the body's immune response.
- The word peptide comes from the Greek phrase "digested in combination." This refers to peptides being digestion products of larger proteins.
How are peptides formed?
Peptides are formed through a process called translation where nucleic acids called mRNA are "read" by a cell's ribosome to produce a chain of amino acids. This chain then folds into the unique 3D shape of a functional peptide or protein. Peptides can also result from cleavage or breakdown of larger proteins into smaller peptide fragments. These fragments often retain biological activity.
Some important types and functions of peptides include:
- Cell signaling peptides: These peptides carry messages between cells and tissues to coordinate bodily processes like growth, metabolism, reproduction, immunity, etc. Examples are the hormone insulin, neuropeptides that influence behavior and mood, and growth factors.
- Antimicrobial peptides: These small peptides are part of the body's immune defense against bacteria, fungi, and viruses. They damage invading pathogen membranes.
- Enzyme inhibitors: There are peptides that can inhibit key enzymes needed by pathogens and regulating metabolism. This provides selective ability to interfere with unwanted processes.
In summary, peptides are short amino acid chains that carry out a wide range of essential functions in the body from signaling to immunity to metabolism. Improving our understanding of how peptides work provides insights into regulating health and combating disease. Let me know if you have any other questions!