Identification of antibacterial peptides from bovine kappa-casein.
The objective of the present study was to identify antimicrobial peptides present in several digests of commercial caseins with gastric enzymes. The most active hydrolysate against Escherichia coli ATCC 25922 and Listeria innocua CECT 910T corresponded to a pepsin digest of bovine kappa-casein. The protein digest was first separated by semipreparative high-performance liquid chromatography (HPLC), and the most active fractions were again subjected to a second chromatographic step. Finally, identification of the active peptides was carried out by online and offline HPLC-electrospray ionization-tandem mass spectrometry. By means of this technique, 21 peptides were identified in the active HPLC fractions. Although most were derived from bovine kappa-casein, some of the identified fragments corresponded to beta-casein and alpha(s)-casein fragments, a result of the presence of small amounts of these proteins in the preparation of kappa-casein. Some of the peptides identified were chemically synthesized and showed antibacterial effects against several gram-positive and gram-negative bacteria. Among the synthesized peptides, kappa-casein f(18-24), f(30-32), and f(139-146) were most effective against all bacteria tested. The antibacterial effect of these peptides is discussed in relation to their amino acid sequences.
López-Expósito
Iván
I
Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
Minervini
Fabio
F
Amigo
Lourdes
L
Recio
Isidra
I
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002364:Caseins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003257:Consumer Product Safety; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D005516:Food Microbiology; D006801:Humans; D006868:Hydrolysis; D008087:Listeria / Q000187:drug effects* / Q000254:growth & development; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D008970:Molecular Weight; D010446:Peptide Fragments / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D002364:Caseins; D010446:Peptide Fragments