A peptide is a short chain of amino acids, typically ranging from 2 to 50, linked together by peptide bonds.
Understanding Peptides
Peptides are formed through a condensation reaction, where a molecule of water is removed, linking the carboxyl group of one amino acid to the amino group of another. This covalent bond is specifically called a peptide bond. As more amino acids join together in this way, they form a peptide chain.
Key Characteristics of Peptides:
- Short Chain: By definition, peptides are shorter than proteins. While the exact cutoff is debated, a common range is 2-50 amino acids. Longer chains are generally considered proteins.
- Amino Acid Building Blocks: Peptides are constructed from amino acids, the same building blocks that make up proteins.
- Peptide Bonds: The amino acids are connected via peptide bonds, formed through dehydration synthesis.
- Variety of Functions: Peptides play diverse roles in biological systems, including acting as hormones, signaling molecules, and antimicrobial agents.
Examples of Peptides:
- Glutathione: An important antioxidant composed of three amino acids (glutamate, cysteine, and glycine).
- Oxytocin: A hormone with nine amino acids that plays a role in social bonding, reproduction, and childbirth.
Difference Between Peptides and Proteins:
The primary difference between peptides and proteins is size. Peptides are smaller chains of amino acids, while proteins are larger and more complex, often exhibiting a defined three-dimensional structure. The specific cutoff in amino acid length used to differentiate peptides from proteins varies, but generally, molecules over 50 amino acids are considered proteins.
