Abstract: A desired protein having the formula:A-B-C-P,wherein (a) A is Lys or Arg, and B and C are arbitrary amino acids, or (b) A is an arbitrary amino acid different from Pro, Lys, and Arg, and B and/or C is Pro is produced from a biosynthetically formed amino-terminally extended protein having the formula:X-A-B-C-P,wherein A, B, C are defined above, and X is an amino acid sequence with an even number of amino acids, of which the first amino acid, seen from the N-terminal end, is different from Lys and Arg, all other am/no acids are different from Pro, Lys and Arg, and all even amino acids are different from Pro, by reaction with the enzyme dipeptidyl aminopeptidase (DAP I). The desired protein is obtained in a pure state. Specifically, P is human growth hormone (hGH). Thus, compositions of hGH may be produced without the presence of Met-hGH.

Abstract: A desired protein having the formula:A-B-C-Pwhereina) A is Lys or Arg, and B and C are arbitrary amino acids, orb) A is an arbitrary amino acid different from Pro, Lys and Arg, and B and/or C is Pro,is produced from a biosynthetically formed amino acid extended protein having the formula:X-A-B-C-Pwherein A, B, C and P are as defined above, and X is an amino acid sequence with an even number of amino acids, of which the first one, seen from the N-terminal end, is different from Lys and Arg, all other uneven amino acids are different from Pro, Lys and Arg, and all even amino acids are different from Pro, by reaction with the enzyme dipeptidyl aminopeptidase (DAP I). The desired protein is obtained in a pure state. Thus, e.g. hGH without content of Met-hGH may be produced by the process.

Abstract: A process for producing ripe human growth hormone is described which comprises introducing into bacteria a recombinant DNA vector comprising a DNA sequence encoding an amino-terminal extended human growth hormone which amino-terminal extension has a negatively charged amino acid sequence and has an even number of amino acids, growing the bacteria such that the amino-terminal extended human growth is expressed, separating the amino-terminal extended human grown hormone from contaminants, cleaving the amino-terminal extension with dipeptidyl aminopeptidase I to obtain ripe human growth hormone and isolating the ripe human growth hormone produced.