Fremgangsmåde til fremstilling af polypeptider meden C-terminal carboxamidgruppe, polypeptider til anvendelse ved fremgangsmåden, fusionsproteiner deraf og dertil egnede DNA-sekvenser, plasmider og værtsorganismer

Polypeptides with a carboxamide carboxyl terminus and a methionine residue, which is optionally bound to a bacterial protein, at the amino end can be prepared by genetic engineering synthesis of the corresponding polypeptide with a glycine residue at the C terminus and the enzymatic conversion thereof into the amino group of the required carboxamide moiety. Peptides which have the amino-acid sequence of growth hormone releasing factor, part sequences thereof or modifications of these peptides can easily be obtained in this way. The genetic engineering synthesis is expediently carried out using two gene fragments which are chemically synthesised from single-stranded smaller fragments. The two gene fragments are then linked enzymatically to give the complete gene, incorporated in a suitable vector, amplified there, the peptide is isolated directly or as fusion protein and is converted enzymatically into the required amide.