Preparation of polypeptides having an amide carboxyl terminal end

摘要

Polypeptides having a carboxamide carboxyl terminal end and a methionine residue, which is optionally bonded to a bacterial protein, on the amino end can be prepared by synthesis by genetic engineering methods of the corresponding polypeptide having at the C terminal end a glycine residue, and conversion of the latter enzymatically into the amino group of the desired carboxamide group. Peptides which have the aminoacid sequence of growth hormone releasing factor, part sequences thereof, or modifications of these peptides, are readily accessible by this means. The synthesis by genetic engineering methods is advantageously carried out via two gene fragments which are synthesized chemically from smaller, single-stranded structural units. The two gene fragments are then linked enzymatically to give the complete gene, which is incorporated into a suitable vector, amplified there, and the peptide is isolated directly or as a fused protein, and is converted enzymatically into the desired amide.