What is a Peptide?
Peptides are short chains of amino acids linked by peptide bonds. Typically, peptides contain less than 50 amino acids. Anything longer is considered a protein.
Peptides play several important roles in the human body:
- Signal transmission - Peptides act as hormones and neurotransmitters to regulate physiological processes
- Immune defense - Antimicrobial peptides help the immune system fight bacteria, viruses, and fungi
- Enzyme regulation - Many enzymes are activated or inhibited by specific peptide sequences
How are peptides formed?
Peptides form when the carboxyl group of one amino acid bonds to the amino group of another through a peptide (or amide) bond. This gives rise to a chain with a free amine group at one end and a free carboxyl group at the other end.
"Peptides are formed by the linkage of amino acids via peptide bonds between the carboxyl and amino groups."
What are some examples of peptides?
- Glutathione - antioxidant peptide that protects cells from damage
- Oxytocin - hormone involved in social bonding, reproduction, and emotions
- Angiotensin - controls blood pressure as part of the renin-angiotensin system
- Endorphins - act as natural pain relievers in the body
What are the key differences between peptides and proteins?
| Peptides | Proteins |
|---|---|
| Short chains, <50 amino acids | Long chains, >50 amino acids | |
| Do not have complex 3D structure | Fold into globular or fibrous shapes |
| Usually synthesized easily | Require ribosomes for synthesis |
So in summary, peptides are short chains of amino acids with key cell signaling roles. While similar to proteins, they lack the length and structural complexity of their larger cousins. Through modern chemistry, we can now synthesize all manner of peptides for medical and research applications.
I hope this gives you a good overview of what peptides are! Visit for more information.