[Genetic engineering of oxytocin: isolation of oxytocinoyllysine].

A hybrid protein, Il-Ox-K, was obtained from cells of E. coli TG1/pTOTEilox strain. The N-terminal sequence of this protein (63 amino acid residues) is a fragment of human interleukin-3, and the C-terminal sequence represents the full amino acid sequence of oxytocin flanked by a lysine residue. The modified oxytocinoyl-Lys containing S-sulfocysteine residues was isolated after tryptic digestion of S-sulfoderivative of the hybrid protein. The modified peptide was converted into the cyclic form containing the disulfide bonds [formula: see text]. Obtaining the oxytocinoyl-Lys proves the possibility of preparing short peptides using the microbiological synthesis.