PRODUCTION OF ACTIVE PROTEINS CONTAINING CYSTINE RESIDUES

The present invention provides a process for producing an active protein having cystine residues. The process comprises cultivating a cell or microorganism harbouring an expression vector capable of expressing the gene for the said cystine containing proteins under conditions whereby the cystine containing protein is secreted by the cell or microorganism and extracting the said protein from the culture medium in active form. The microorganism or cell selected is one that is capable of secreting disulphide-bonded proteins. The expression vector contains a regulatory nucleotide sequence corresponding to that portion of the host cell or microorganism gene responsible for regulating the expression and secretion of homologous disulphide-bonded proteins. The regulatory sequence is operably linked to a nucleotide sequence encoding the desired protein having cystine residues. The invention avoids the difficult and often expensive task of chemically renaturating cystine containing proteins.