|Details:|| Peptides (from Gr.: πεπτός, peptós "digested"; derived from πέσσειν, péssein "to digest") are natural biological or artificially manufactured short chains of amino acid monomers linked by peptide (amide) bonds.
The covalent chemical bonds are formed when the carboxyl group of one amino acid reacts with the amide group of another. The shortest peptides are dipeptides, consisting of 2 amino acids joined by a single peptide bond, followed by tripeptides, tetrapeptides, etc. A polypeptide is a long, continuous, and unbranched peptide chain. Hence, peptides fall under the broad chemical classes of biological oligomers and polymers, alongside nucleic acids, oligosaccharides and polysaccharides, etc.
Peptides are distinguished from proteins on the basis of size, and as an arbitrary benchmark can be understood to contain approximately 50 or fewer amino acids. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, or to another protein or other macromolecule (DNA, RNA, etc.), or to complex macromolecular assemblies. Finally, while aspects of the lab techniques applied to peptides versus polypeptides and proteins differ (e.g., the specifics of electrophoresis, chromatography, etc.), the size boundaries that distinguish peptides from polypeptides and proteins are not absolute: long peptides such as amyloid beta have been referred to as proteins, and smaller proteins like insulin have been considered peptides.
Amino acids that have been incorporated into peptides are termed "residues" due to the release of either a hydrogen ion from the amine end or a hydroxyl ion from the carboxyl end, or both, as a water molecule is released during formation of each amide bond. All peptides except cyclic peptides have an N-terminal and C-terminal residue at the end of the peptide (as shown for the tetrapeptide in the image).
Posted by: RDM
2017-09-28 19:44:27 MST
| Peptides are versatile biological molecules with a wide range of potential applications. Recent developments in peptide synthesis have enabled the preparation of both naturally occurring and novel peptidic structures of great complexity. This has led to the expanded use of peptides and peptidomimetics in drug development as well as growing interest in the development of peptide-based materials to underpin cutting edge technologies.
Research articles covering all areas of peptide chemistry from peptide synthesis and chemical ligation; isolation and characterization of new peptidic natural products through to biological and medicinal applications; the study of peptide self-assembly and the development of novel peptide-based materials are welcomed for inclusion in this special issue for Molecules.
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