Peptides are short chains of amino acids linked by peptide bonds. Typically, peptides contain less than 50 amino acids. Anything larger is considered a protein.
Peptides serve many important functions in the human body:
- As signaling molecules
- As hormones
- As antibiotics
- As growth factors
Key Terms
- Amino acids: The building blocks of peptides and proteins. There are 20 common amino acids that join together to form peptides.
- Peptide bonds: The bonds between amino acids, formed when the carboxyl group of one amino acid reacts with the amino group of another. This forms a peptide linkage.
- Protein: A long chain of amino acids, typically over 50 amino acids. Proteins take on complex 3D shapes to carry out their functions.
Some examples of peptides include:
- Oxytocin - the "love hormone" involved in social bonding
- Endorphins - natural pain relievers
- Angiotensin - helps control blood pressure
How are peptides created?
Peptides form when ribosomes translate mRNA transcripts and start stringing together amino acids. As the amino acid chain elongates, it emerges from the ribosome and folds into its functional 3D form.
"A peptide is like a short sentence written with amino acids rather than letters"
What are some medical uses of peptides?
- Some peptides like insulin help regulate blood sugar levels in diabetes patients when injected.
- Specialized peptides can act as "tumor homing molecules," binding to cancer cells and delivering chemotherapy drugs right to the source.
- Antimicrobial peptides on our skin provide the first line of defense against bacteria, viruses, and fungi. Many researchers are studying antimicrobial peptides as a new source of antibiotics.
In summary, peptides are short chains of amino acids that carry out myriad functions in the human body. From regulating physiology to fighting off pathogens, peptides impact health in many ways. An improved understanding of peptides could lead to new therapeutic applications, biomarkers of disease, and novel antibiotics.