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Caseicin A [id=CAA0003]

Synonym: Alphas1-casein f(21-29)

Producer Organism : Native Protein : Production Method :
Cow αs1-casein Enzymatic hydrolysis and Purification with LC method
Activity : Antibacterial
Target Organisms :

Gram-positive: Active against Lactobacillus bulgaricus ATCC 11842 DPC5383, Listeria innocua DPC3306, Streptococcus mutans DPC4069 at 0.05 mM.

Gram-negative: Active against Escherichia coli JM109 DPC6053, Escherichia coli O157:H7 DPC6054, Escherichia coli O157:H7 DPC6055, Enterobacter sakazakii ATCC 12868 DPC6090, Enterobacter sakazakii NCTC 8155 DPC6091 at 0.05 mM.

NOTE: No activity against Staphylococcus aureus DPC5246 at 0.05 mM .

Description :
Production method: Lactobacillus acidophilus DPC6026 proteinase hydrolysis and purification with LC method.

Length : 9 Mass (Da): 1 049.81 Common Amino Acids : Q
Isolectric Point : 7.55 Net Charge : 1 Absent Amino Acids : ACDFMNRSTVWY
Basic Residues : 2 Acidic Residues : 1 Hydrophobic Residues : 2
Polar Residues : 1 Boman Index : -17.32 Hydropathy Index : -1.256
Aliphatic Index : 86.67 Instability Index : 0 Extinction Coefficient :
Absorbance 280nm : 0

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.

Multiple Sequence Alignment (MSA)


1 CAA0001 100.0%  RPKHPIKHQGLPQEVLNENLLRF 

2 CAA0003 100.0%  -----IKHQGLPQE--------- 
3 CAA0004 100.0%  --------------VLNENLLR- 

Citation: 1

Casein-derived antimicrobial peptides generated by Lactobacillus acidophilus DPC6026

Cited Entries: CAA0003, CAA0004, CAA0006

Authors:Hayes, M., Ross, R.P., Fitzgerald, G.F., Hill, C., Stanton, C.
Journal: Applied and Environmental Microbiology 2006, 72(3).
Abstract: Three peptides produced by a Lactobacillus acidophilus DPC6026 fermentation of sodium caseinate and showing antibacterial activity against pathogenic strains Enterobacter sakazakii ATCC 12868 and Escherichia coli DPC5063 were characterized. These peptides were all generated from bovine {alpha}s1-casein and identified as IKHQGLPQE, VLNENLLR, and SDIPNPIGSENSEK. These peptides may have bioprotective applicability and potential use in milk-based formula, which has been linked to E. sakazakii infection in neonates.
Citation: 2

Altering the Composition of Caseicins A and B as a Means of Determining the Contribution of Specific Residues to Antimicrobial Activity

Cited Entries: CAA0003, CAA0004

Authors:Norberg, S., O’Connor, P. M., Stanton, C., Ross, R. P., Hill, C., Fitzgerald, G. F., Cotter, P. D.
Journal: Applied and Environmental Microbiology 2011, 77(7): 6.
CrossRef External Link
Abstract: Caseicin A (IKHQGLPQE) and caseicin B (VLNENLLR) are antimicrobial peptides generated through the bacterial fermentation of sodium caseinate, and on the basis of this and previous studies, they are active against many Gram-negative pathogens (Cronobacter sakazakii, Cronobacter muytjensii, Salmonella enterica serovar Typhimurium, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas fluorescens) as well as the Gram-positive organism Staphylococcus aureus. Here we describe further studies with the aim of establishing the importance of specific (charged and nonpolar aliphatic) residues within the caseicin peptides and the effects that they have on the bacteria listed above. In order to achieve our objective, we created four derivatives of each caseicin (A1 to A4 and B1 to B4) in which specific residues were altered, and results obtained with these derivatives were compared to wild-type caseicin activity. Although conversion of cationic residues to alanine in caseicins B1 (R8A change), A1 (K2A), A2 (H3A), and A3 (K2A-H3A) generally resulted in their activity against microbial targets being reduced or unaltered, C. sakazakii DPC6440 was unusual in that it displayed enhanced sensitivity to three peptides (caseicins A1, A3, and B2) in which positively charged residues had been eliminated. While the replacement of leucine with alanine in selected variants (B3 and B4) resulted in reduced activity against a number of strains of Cronobacter and, in some cases, S. Typhimurium, these changes enhanced the activities of these peptides against DPC6440 and a number of S. aureus strains. It is thus apparent that the importance of specific residues within the caseicin peptides is dependent on the strain being targeted.
Citation: 3

Inhibition of verocytotoxigenic Escherichia coli by antimicrobial peptides caseicin A and B and the factors affecting their antimicrobial activities

Cited Entries: CAA0003, CAA0004

Authors:McDonnell, M. J., Rivasa, L., Burgessa, C. M., Fanningb, S., Duffy, G.
Journal: International Journal of Food Microbiology 2011, 153(3): 9.
CrossRef External Link
Abstract: The antimic robial activities of caseicin A and B antimicrobial peptides (AMPs) were assessed against a selection of verocytotoxigenic Escherichia coli (VTEC) strains (n = 11), other bacterial pathogenic and spoilage bacteria (n = 7), using a model broth system. The ability of the AMPs to retain their antimicrobial activities against a strain of E. coli O157:H7 380-94 under various test conditions (pH, temperature, water activity, sodium chloride concentrations, inoculum size and the presence of competitive microflora) was assessed and the minimum inhibitory concentrations (MIC) and number of surviving E. coli O157:H7 calculated. The mean number of VTEC surviving after exposure to 2 mg/ml caseicin A and B was reduced by 4.96 and 4.19 log10 cfu/ml compared to the respective controls. The susceptibility of E. coli O157:H7 to the caseicin AMPs decreased as temperature, pH, water activity and inoculum size were reduced. The presence of sodium chloride (0.5–2.5%) did not affect the activity of caseicin A (p > 0.05), however it did inhibit the activity of caseicin B. The presence of a competitive microflora cocktail did not significantly (p > 0.05) affect the activities of the AMPs for the majority of the concentrations tested. Using a quantitative PCR assay, the levels of verotoxins (vt1 and vt2) expressed by E. coli O157:H7 following exposure to a sub-inhibitory concentration (0.5 mg/ml) of caseicin A showed that the verotoxin levels did not differ from the levels produced by the control cultures. The antimicrobial activity of caseicin A against E. coli O157:H7 was also tested in a model rumen system, however concentrations of ≥ 2 mg/ml did not significantly (p > 0.05) reduce E. coli O157:H7 numbers in the model system over a 24 h period. The application of caseicin AMPs in food and/or animal production may be valuable in combination with other antimicrobials although further research is required.
Keywords: Escherichia coli; Caseicin; Antimicrobial peptides; Rumen

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