EFFICIENT PRODUCTION OF CASOXIN-D, A BRADYKININ AGONIST PEPTIDE DERIVED FROM HUMAN CASEIN, BY BACILLUS-BREVIS

We efficiently produced a small peptide by the host-vector system usin g Bacillus brevis as a host, DNA encoding the physiologically function al casoxin D, composed of seven amino acids, was ligated in tandem, An expression-secretion vector containing DIVA, which codes for a fusion protein of epidermal growth factor-casoxin D pentamer, was constructe d, B. brevis transformed with this plasmid produced about 0.5 g/liter of the fusion protein in the culture supernatant, The fusion protein w as purified with ammonium sulfate fractionation from the supernatant a nd digested with two kinds of proteinases, A peptide well separated by high pressure liquid chromatography,vas identified as biologically ac tive casoxin D.