
Full text loading...
A bacteriocin produced by Pediococcus acidilactici has been purified to homogeneity by a rapid and simple four-step purification procedure which includes ammonium sulphate precipitation, chromatography with a cation-exchanger and Octyl Sepharose, and reverse-phase chromatography. The purification resulted in an approximately 80000-fold increase in the specific activity and about a 6-fold increase in the total activity. The amino acid composition and sequencing data indicated that the bacteriocin contained 43–44 amino acid residues. The predicted M r and isoelectric point of the bacteriocin are about 4600 and 8.6, respectively. Comparing the amino acid sequence of this bacteriocin with the sequences of leucocin A-UAL 187, sakacin P and curvacin A (bacteriocins produced by Leuconostoc gelidum, Lactobacillus sake and Lactobacillus curvatus, respectively) revealed that all four bacteriocins had in their N-terminal region the sequence Tyr-Gly-Asn-Gly-Val-Xaa-Cys, indicating that this concensus sequence is of fundamental importance for this group of bacteriocins. The bacteriocin from P. acidilactici and sakacin P were very similar, having at least 25 common amino acid residues. The sequence similarity was greatest in the N-terminal half of the molecules – 17 of the first 19 residues were common – indicating the fundamental importance of this region. Leucocin A-UAL 187 and curvacin A had, respectively, at least 16 and 13 amino acid residues in common with the bacteriocin from P. acidilactici.