Introduction to Peptides

Peptides are organic compounds made up of amino acids connected by peptide bonds. These bonds form when two amino acids combine, creating a molecule essential for various biological functions. Peptides are found naturally in the human body and are synthesized in laboratories for research purposes. Their study holds significant promise in fields like health and pharmaceuticals.

How Are Peptides Formed?

Peptides form naturally in the body through ribosomal and non-ribosomal processes, or they can be synthetically created in the lab. Modern methods such as solid-phase peptide synthesis allow the production of diverse peptides for research. The discovery of synthetic peptides dates back to 1901, with Oxytocin being one of the first peptides synthesized in 1953.

Peptide Classification

Peptides are categorized based on their amino acid count. For example:

Dipeptides contain two amino acids.
Oligopeptides include fewer than ten amino acids.
Polypeptides have more than ten amino acids, often considered proteins when they exceed 40-50 amino acids.

There are exceptions, like insulin, which is often referred to as a peptide despite being a protein.

Types of Peptides

Ribosomal Peptides: Produced by the translation of mRNA, these peptides play roles in hormone signaling and defense mechanisms.
Non-Ribosomal Peptides: Synthesized by peptide-specific enzymes, these peptides often form intricate cyclic structures and are found in plants and fungi.
Milk Peptides: Derived from milk proteins and important for nutritional and biological functions.
Peptones: These peptides are used in laboratories to grow bacteria and fungi.

Key Peptide Terms

Amino Acids: The building blocks of peptides.
Cyclic Peptides: Peptides with a ring structure, such as Melanotan-2.
Peptide Bond: The covalent bond linking amino acids in a peptide.
Peptide Mapping: A technique used to identify the amino acid sequence of peptides or proteins.
Peptide Libraries: Collections of peptides used for biochemical research.