κ-casein f(43-97) [id=CAK0001]

Synonym: Kappa-casein f(63-117) immature protein

Producer Organism : Native Protein : Production Method :
Human κ-casein Enzymatic hydrolysis and Purification with LC method/Synthetic
Activity : Antibacterial, antifungal
Target Organisms :

Gram-positive: Active against Staphylococcus carnosus TM 300.

Gram-negative: Active against Escherichia coli BL 21.

Yeast: Not precised .

Description :
Production method: Pepsin hydrolysis and purification with LC method/Synthetic.

Length : 55 Mass (Da): 6 431.79 Common Amino Acids : P
Isolectric Point : 11.77 Net Charge : 10 Absent Amino Acids : CDEGKMW
Basic Residues : 10 Acidic Residues : 0 Hydrophobic Residues : 16
Polar Residues : 14 Boman Index : -129.59 Hydropathy Index : -0.833
Aliphatic Index : 70.91 Instability Index : 0 Extinction Coefficient : 7450
Absorbance 280nm : 137.96

Wheel representation

Hydrophobicity plot

Red solid plot : values according to the hydrophobicity scale of Kyte and Doolittle (reference paper).
Yellow dashed plot : Experimentally determined hydrophobicity scale for proteins at membrane interfaces(reference paper).
Green dotted-dashed plot : prediction of transmembrane helices (reference paper). In this scale (unlike the others), more negative values reflect greater hydrophobicity.

Citation: 1

Purification of novel peptide antibiotics from human milk

Cited Entries: CAK0001

Authors:Liepke, C., Zucht, H.-D., Forssmann, W.-G., Stndker, L.
Journal: Journal of Chromatography B: Biomedical Sciences and Applications 2001, 752(2).
CrossRef External Link
Abstract: A strategy was established for the identification of novel antimicrobial peptides from human milk. For the generation of bioactive peptides human milk was acidified and proteolyzed with pepsin simulating the digest in infants stomachs. Separation of proteins and resulting fragments was performed by means of reversed-phase chromatography detecting the antimicrobial activity of each fraction using a sensitive radial diffusion assay. In order to avoid the purification of the known abundant antimicrobial milk protein lysozyme, it was identified in HPLC fractions by its enzymatic activity and by matrix-assisted laser desorption ionization–mass spectrometry (MALDI–MS). On condition that lysozyme was not detectable and antibacterial activity of HPLC fractions was caused by a peptide, which was confirmed by proteolytic cleavage leading to a loss of activity, further purification was performed by consecutive chromatographic steps guided by the antibacterial assay. Using this strategy, an as yet unknown casein fragment exhibiting antimicrobial activity was purified in addition to antimicrobial lactoferrin fragments. The new antimicrobial peptide resembles a proteolytic fragment of human casein-κ (residues 63–117) and inhibits the growth of Gram-positive, Gram-negative bacteria, and yeasts. Our results confirm that antimicrobially-active peptides are liberated from human milk proteins during proteolytic hydrolysis and may play an important role in the host defense system of the newborn.
Keywords: Peptide analysis

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