Schering Aktiengesellschaft

Gerhard Siewert

Joachim Daum

Werner Boidol

Michael Topert

Hartmut Seliger

A process for cleavage of a protein (a) sequence from a protein containing the tetrapeptide sequence Pro-Xyz-Gly-Pro, wherein Xyz can be any desired amino acid, and reacting the protein with a collagenase whereby the Xyz-Gly bond is selectively cleaved, thereby producing a protein with the sequence Gly-Pro at its N-terminal end; or (b) containing the sequence Met-Pro; and subsequently selectively cleaving the glycine or methionine residue from the N-terminal end of the product protein with an aminoacylproline aminopeptidase and selectively cleaving the proline residue therefrom with a proline aminopeptidase; or subsequently selectively cleaving the Gly-Pro or Met-Pro residue from the N-terminal end of the produced protein using a postproline dipeptidylaminopeptidase. In a special embodiment, the protein which is split contains the sequence -Zxy-Uvw-Pro- on the carboxy end of the sequence Pro-Xyz-Gly-Pro, wherein Zxy and Uvw are independently any natural amino acid in the genetic code except Pro, whereby after the collagenase reaction, there is produced a protein with the sequence Gly-Pro-Zxy-Uvw-Pro at the N-terminal end. This is split by subsequently selectively cleaving the Pro-Zxy-bond by treating the protein with postproline dipeptidylaminopeptidase (PPDA), thereby producing protein having the sequence Zxy-Uvw-Pro at its N-terminal end, followed by cleaving the Zxy acid from the resultant protein by treating the latter with leucine aminopeptidase.

Process for the specific cleavage of protein sequences from proteins

PhoA mutant E. coli SB44, prepared by mutation of E. coli HB101 with an N-nitroso compound, can be used to identify and isolate recombinant plasmids into which a phoA gene has been incorporated. These plasmids can be used to transform bacteria which can be cloned and incubated to provide alkaline phosphatase in high yield. Moreover, these plasmid vectors can be modified in various ways so that the N-terminal amino acid sequence of phoA is followed in reading phase by the DNA coding for some other protein. In turn, these new plasmids can be used to transform bacteria which can be cloned and incubated to produce fusion proteins comprising the desired other protein in high yield and outside of the cell membrane in the periplasmatic space.

Growing community of inventors

Berlin, Germany

Gerhard Siewert