pentapeptide

A pentapeptide is a peptide composed of five amino acids linked by four peptide bonds. It has an N-terminal amino group and a C-terminal carboxyl group, and its properties depend on the identities and order of the five residues. As a short chain, a pentapeptide is typically flexible and may not form a defined secondary structure on its own; the side chains of the constituent amino acids influence its conformation and interactions. Its molecular weight is roughly in the range of 500 to 700 daltons, depending on the specific amino acids and terminal groups.

Synthesis and analysis: Pentapeptides are commonly prepared by solid-phase peptide synthesis and purified by high-performance liquid chromatography. They are usually characterized by mass spectrometry and, when needed, complementary analytical methods to confirm sequence and purity.

Functions and applications: In biochemical research, pentapeptides serve as substrates or inhibitors in enzyme assays, as recognition motifs in binding studies, and as standards or controls in analytical workflows. They provide simple model systems for studying proteolysis, peptide transport, and receptor interactions. Cyclic pentapeptides—formed by cyclization of the linear chain—are of particular interest due to enhanced stability and a range of biological activities.

Nomenclature and variants: The sequence is written from N-terminus to C-terminus, for example a hypothetical pentapeptide could be abbreviated as X1-X2-X3-X4-X5. The term also applies to pentapeptide motifs embedded in larger proteins, known as pentapeptide repeats, which occur in various biological contexts.