The use of gel-filtration for the isolation of pure nisin from commercial products.

Commercial nisin was fractionated using a Bio-Gel P-10 column and ion-exchange chromatography on CM-sephadex C-25. Pure nisin having a titre of 40 X 10(6) units per gram was obtained. In polyacrylamide-gel electrophoresis the pure nisin gave three bands. It is suggested that heterogeneity of nisin is due to the presence of several biological polypeptides. The pure nisin is digested by chymotrypsin but it is not affected by TPCK-trypsin and pepsin.