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Peptides are short chains of amino acids linked by peptide bonds. Typically, peptides contain 2-50 amino acids. Anything longer is usually referred to as a protein. Some key features of peptides:
- Size: As mentioned, peptides are usually small, containing just 2-50 amino acids. This distinguishes them from larger proteins.
- Function: Peptides have a wide range of biological functions. Some common examples include acting as hormones, neurotransmitters, or antibiotics.
- Structure: The peptide bond links the carboxyl group of one amino acid to the amino group of the next amino acid. This creates the peptide backbone. The sequence and composition of amino acid R groups off of this backbone impart the structure and function of the peptide.
- Synthesis: Peptides can be synthesized chemically, using solid-phase peptide synthesis. This builds the peptide bond-by-bond on a solid resin support. Biosynthetically, peptides are produced when proteins are degraded.
Some examples of important peptides include:
- Oxytocin - this 9 amino acid peptide acts as a hormone. It plays important roles in social bonding, reproduction, childbirth, and lactation.
- Glutathione - this tripeptide antioxidant helps prevent damage to cells by reactive oxygen species.
- Gramicidin S - this cyclic peptide from bacteria has antibiotic effects and helps disrupt cell membranes.
In summary, peptides are short chains of amino acids that have a wide range of structure and function in biology. Ranging from just 2-50 amino acids in length, peptides act as hormones, neurotransmitters, antibiotics, and more. Their sequence of amino acids imparts their 3D shape and function. Understanding the diversity of peptides is important for fields ranging from biomedicine to biotechnology.