title: Identification of novel antibacterial peptides isolated from a commercially available casein hydrolysate by autofocusing technique.
abstract: Autofocusing, as a simple and safe technique, was used to fractionate casein hydrolysate based on the amphoteric nature of its peptides. The antibacterial activity of casein hydrolysate and its autofocusing fractions (A1-10) was examined against Escherichia coli and Bacillus subtilis. The basic fraction A9 exhibited the highest activity with minimum inhibitory concentration (MIC) of 150 μg/mL, whereas casein hydrolysate showed MIC values ranging from 2000 to 8000 μg/mL. The antibacterial peptides in A9 were purified by using a series of size exclusion and reversed phase chromatographies. Three peptides exhibited the most potent antibacterial activity with MIC values ranging from 12.5 to 100 μg/mL. These peptides were generated from α(s2)-casein, α(s1)-casein, and κ-casein and identified as K165 KISQRYQKFALPQYLKTVYQHQK188, I6KHQGLPQEV15, and T136EAVESTVATL146, respectively. Therefore, the results revealed that casein hydrolysate had potent antibacterial peptides that could be isolated by autofocusing technique.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Life & Environmental Sciences, Kyoto Prefectural University, Shimogamo, Kyoto, Japan.
authors.forename: Hend A
authors.initials: HA
authors.lastname: Elbarbary
authors.forename: Adham M
authors.initials: AM
authors.lastname: Abdou
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Park
authors.forename: Hamdi A
authors.initials: HA
authors.lastname: Mohamed
authors.forename: Kenji
authors.initials: K
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects; D002364:Caseins / Q000737:chemistry* / Q000494:pharmacology; D002417:Cattle; D002850:Chromatography, Gel; D056148:Chromatography, Reverse-Phase; D004926:Escherichia coli / Q000187:drug effects; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D020539:Sequence Analysis, Protein
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D002364:Caseins; D010446:Peptide Fragments; C475729:casein hydrolysate