PEPTIDES

**Limiting references (this place does not cover):** - Peptides containing beta-lactam rings -> C07D - Cyclic dipeptides not having in their molecule any other peptide link than those which form their ring; e.g. piperazine-2,5-diones -> C07D - Ergot alkaloids of the cyclic peptide type -> C07D519/02 - Enzymes -> C12N - Genetic engineering processes for obtaining peptides -> C12N15/00 - Peptides and proteins obtained by fermentation or enzyme-using processes are classified in -> C12P21/00 - C12P21/06 - Electrolytic production of organic compounds -> C25B3/00

**Glossary:** - Amino acid: compounds in which at least one amino acid group and at least one carboxylic group are bound to the same carbon skeleton and the nitrogen atom of the amino group may be part of a ring - Normal peptide link: a link between an alpha-amino group of an amino acid and the carboxylic group in position 1 of another alpha-amino acid - Abnormal peptide link: a link where at least one of the linked amino acids is not an alpha- amino acid or a link formed by at least one carboxyl or amino group being a part of the side chain of an alpha-amino acid. Peptide compounds containing at least two amino acid units, which are bound through at least one normal peptide link, including oligopeptides, polypeptides and proteins. - Linear peptides: may comprise rings formed through S-S bridges, or through an hydroxy or a mercapto group of an hydroxy- or a mercapto-amino acid and the carboxyl group of another amino acid (e.g. peptide lactones) but do not comprise rings which are formed only through peptide links. - Cyclic peptides: comprising at least one ring formed only through peptide links; the cyclisation may occur only through normal peptide links or through abnormal peptide links, e.g. through the 4-amino group of 2,4-diamino-butanoic acid. Thus, cyclic compounds in which at least one link in the ring is a non-peptide link are considered as' linear peptides'. - Depsipeptides: compounds containing a sequence of at least two alpha-amino acids and at least one alpha-hydroxy carboxylic acid, which are bound through at least one normal peptide link and ester link, derived from the hydroxy carboxylic acids - Linear depsipeptides: may comprise rings formed through S-S bridges, or through an hydroxy or a mercapto group of an hydroxy- or mercapto-amino and and the carboxyl group of another amino- or hydroxy-acid but do not comprise rings formed only through peptide or ester links derived from hydroxy carboxylic acids, e.g. Gly-Ala-Gly-OCH2CO2H and Gly-OCH2CO-Ala-Gly are considered as "linear depsipeptides, but HOCH2CO-Gly-Ala-Gly does not contain an ester link, and is thus a derivative of Gly-Ala-Gly which is covered by C07K5/08 - Cyclic depsipeptides: are peptides containing at least one ring formed only through peptide or ester link - derived from hydroxy carboxylic acids -, e.g. Gly-Ala-Gly-OCH2CO - Hybrid peptides: are peptides produced through fusion or covalent binding of two or more heterologous peptides.