Abstract: The invention at hand describes a method for the cyclization of peptides and proteins in which linear thioesters serve as substrates. The cyclization is catalyzed by thioesterase domains of NRPS or PKS cyclases. The substrates according to the present invention are composed of one linear peptide on which a charge-stabilized aromatic, heteroaromatic or araliphatic leaving group is bound. These substrates lead to higher yields and reaction rates than linear peptides able to be cyclized with methods known so far and, furthermore, allow the cyclization of such peptides which were previously not able to be cyclized.

Abstract: Novel tailor-made artificial non-ribosomal peptide synthetases (NRPSs) for non-ribosomal synthesis and/or modification of peptides of a predetermined length and composition and/or for modification of individual amino acids are described. The fusion of building units of said peptide synthetases in particular linker regions makes it possible to specifically prepare by means of “modular molecule construction kits” NRPSs which are capable of synthesizing peptides of a desired structure.

Abstract: Novel tailor-made artificial non-ribosomal peptide synthetases (NRPSs) for non-ribosomal synthesis and/or modification of peptides of a predetermined length and composition and/or for modification of individual amino acids are described. The fusion of building units of said peptide synthetases in particular linker regions makes it possible to specifically prepare by means of “modular molecule construction kits” NRPSs which are capable of synthesizing peptides of a desired structure.

Abstract: A simple mutant of the natural asparagine oxygenase comprises at least the amino acids 13 to 318 of the natural asparagine oxygenase AsnO. In this protein according to the present invention, comprising at least the amino acids 13-318 of AsnO D241N, the amino acid residue at position 241 of the natural asparagine oxygenase AsnO is exchanged from aspartate (D) to asparagine (N). The protein according to the present invention, comprising at least the amino acids 13-318 of AsnO D241N, is produced by means of a directed mutagenesis from the AsnO wild type, cloning of this expression plasmid into a vector, transformation of the vector plasmid construction into a host organism and expression of the recombinant protein. The protein according to the present invention is suitable for the chemoenzymatic and enantioselective production of L-threo-hydroxyaspartate from L-aspartate. The protein is substrate-specific and converts quantitatively L-aspartate into L-threo-hydroxyaspartate.

Abstract: The invention at hand describes a method for the cyclization of peptides and proteins in which linear thioesters serve as substrates. The cyclization is catalyzed by thioesterase domains of NRPS or PKS cyclases. The substrates according to the present invention are composed of one linear peptide on which a charge-stabilized aromatic, heteroaromatic or araliphatic leaving group is bound. These substrates lead to higher yields and reaction rates than linear peptides able to be cyclized with methods known so far and, furthermore, allow the cyclization of such peptides which were previously not able to be cyclized.

Abstract: The present invention relates to a new, microbiological, method for the production of &agr;-L-aspartyl-L-phenylalanine (Asp-Phe) from the substrates L-aspartic acid (L-Asp) and L-phenylalanine (L-Phe) wherein the substrates are contacted, in the presence of ATP, with a non-ribosomal dipeptide synthetase comprising two minimal modules connected by one condensation domain wherein the N- resp. C-terminal modules are recognizing L-Asp and L-Phe, respectively, and the latter module is covalently bound at its N-terminal end to the condensation domain, and wherein each of these minimal modules is composed of an adenylation domain and a 4′-phosphopantetheinyl cofactor containing thiolation domain, and that the Asp-Phe formed is recovered. The present invention also relates to novel DNA fragments or combination of DNA fragments encoding a new Asp-Phe dipeptide synthetase, micro-organisms containing such DNA fragments, as well as to the new Asp-Phe dipeptide synthetases itself.