title: Virtual screening of a milk peptide database for the identification of food-derived antimicrobial peptides.
abstract: METHODS
  Milk provides a wide range of bioactive substances, such as antimicrobial peptides and proteins. Our study aimed to identify novel antimicrobial peptides naturally present in milk.
  
  
  RESULTS
  The components of an endogenous bovine milk peptide database were virtually screened for charge, amphipathy, and predicted secondary structure. Thus, 23 of 248 screened peptides were identified as candidates for antimicrobial effects. After commercial synthesis, their antimicrobial activities were determined against Escherichia coli NEB5α, E. coli ATCC25922, and Bacillus subtilis ATCC6051. In the tested concentration range (<2 mM), bacteriostatic activity of 14 peptides was detected including nine peptides inhibiting both Gram-positive and Gram-negative bacteria. The most effective fragment was TKLTEEEKNRLNFLKKISQRYQKFΑLPQYLK corresponding to αS2 -casein151-181 , with minimum inhibitory concentration (MIC) of 4.0 μM against B. subtilis ATCC6051, and minimum inhibitory concentrations of 16.2 μM against both E. coli strains. Circular dichroism spectroscopy revealed conformational changes of most active peptides in a membrane-mimic environment, transitioning from an unordered to α-helical structure.
  
  
  CONCLUSIONS
  Screening of food peptide databases by prediction tools is an efficient method to identify novel antimicrobial food-derived peptides. Milk-derived antimicrobial peptides may have potential use as functional food ingredients and help to understand the molecular mechanisms of anti-infective milk effects.
authors.affiliation: Food Chemistry Unit, Department of Chemistry and Pharmacy, Emil-Fischer-Center, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
authors.forename: Yufang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Medicinal Chemistry Unit, Department of Chemistry and Pharmacy, Emil-Fischer-Center, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Eichler
authors.affiliation: Food Chemistry Unit, Department of Chemistry and Pharmacy, Emil-Fischer-Center, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Pischetsrieder
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D002417:Cattle; D002942:Circular Dichroism; D030562:Databases, Protein; D008826:Microbial Sensitivity Tests; D008894:Milk Proteins / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D017433:Protein Structure, Secondary
chemical_list: D023181:Antimicrobial Cationic Peptides; D008894:Milk Proteins
keywords: Antimicrobial peptide; Circular dichroism; Milk; Peptide database; Virtual screening