Production of a biologically active variant form of recombinant human secretin.

A biologically active variant form of recombinant human secretin was produced using a gene fusion system designed to facilitate the purification of the protein. The fusion protein was recovered from the culture medium of Escherichia coli by IgG affinity chromatography, and recombinant secretin was released by cyanogen bromide treatment. A novel approach involving addition of a C-terminal Gly-Lys-Arg extension, was used to overcome the lack of amidation of recombinant proteins in Escherichia coli. The biological activity of the recombinant variant of secretin was at least 80% of the porcine secretin standard.