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LF f(16-40) modified [id=LFH0077]

Producer Organism : Native Protein : Production Method :
Human Lactoferrin (LF) Synthetic
Activity : Antibacterial, antifungal
Target Organisms :

Gram-positive: Staphylococcus aureus MRS 3525 (MMC99=50 g/ml).

Gram-negative: Escherichia coli O6K5 (MMC99=100 g/ml).

Yeast: Candida albicans ATCC 64549 (MMC99=37 g/ml).

Description :
Production method: Synthetic.

Eleventh residue replaced with alanine.
Based on the Ala substitutions in LFH0032 and LFH0036, or to Lys in LFH0067, the same changes were introduced in the larger lactoferricin-like LFH0075 in order to find out whether enhanced antimicrobial activities also would be expressed in the double-sized molecule compared to the native sequence. The change of N26 to Ala improved the activity only against C. albicans (LFH0077). The increased charge, by changing Q24 to Lys, improved the microbicidal activity significantly against both E. coli and C. albicans (LFH0078). LFH0076 was lower efficient compared to that of the natural sequence (Citation: 1).
Length : 25 Mass (Da): 2 977.28 Common Amino Acids : R
Isolectric Point : 11.58 Net Charge : 6 Absent Amino Acids : DHLNY
Basic Residues : 7 Acidic Residues : 1 Hydrophobic Residues : 7
Polar Residues : 5 Boman Index : -72.41 Hydropathy Index : -0.8
Aliphatic Index : 46.8 Instability Index : 0 Extinction Coefficient : 5625
Absorbance 280nm : 234.38

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

Structure-microbicidal activity relationship of synthetic fragments derived from the antibacterial alpha-helix of human lactoferrin

Cited Entries: LFH0011, LFH0012, LFH0013, LFH0014, LFH0015, LFH0021, LFH0027, LFH0029, LFH0030, LFH0031, LFH0032, LFH0033, LFH0034, LFH0035, LFH0036, LFH0037, LFH0038, LFH0039, LFH0040, LFH0041, LFH0045, LFH0055, LFH0066, LFH0067, LFH0068, LFH0069, LFH0070, LFH0071, LFH0072, LFH0073, LFH0074, LFH0075, LFH0076, LFH0077, LFH0078

Authors:Haversen, L., Kondori, N., Baltzer, L., Hanson, L.A., Dolphin, G.T., Duner, K., Mattsby-Baltzer, I.
Journal: Antimicrobial Agents and Chemotherapy. 2010, 54(1).
Abstract: There is a need for new microbicidal agents with therapeutic potential due to antibiotic resistance in bacteria and fungi. In this study, the structure-microbicidal activity relationship of amino acid residues 14 to 31 (sequence 14-31) from the N-terminal end, corresponding to the antibacterial {alpha}-helix of human lactoferrin (LF), was investigated by downsizing, alanine scanning, and substitution of amino acids. Microbicidal analysis (99% killing) was performed by a microplate assay using Escherichia coli, Staphylococcus aureus, and Candida albicans as test organisms. Starting from the N-terminal end, downsizing of peptide sequence 14-31 showed that the peptide sequence 19-31 (KCFQWQRNMRKVR, HL9) was the optimal length for antimicrobial activity. Furthermore, HL9 bound to lipid A/lipopolysaccharide, as shown by neutralizing endotoxic activity in a Limulus assay. Alanine scanning of peptide sequence 20-31 showed that Cys20, Trp23, Arg28, Lys29, or Arg31 was important for expressing full killing activity, particularly against C. albicans. Substituting the neutral hydrophilic amino acids Gln24 and Asn26 for Lys and Ala (HLopt2), respectively, enhanced microbicidal activity significantly against all test organisms compared to the amino acids natural counterpart, also, in comparison with HL9, HLopt2 had more than 10-fold-stronger fungicidal activity. Furthermore, HLopt2 was less affected by metallic salts than HL9. The microbicidal activity of HLopt2 was slightly reduced only at pH 7.0, as tested in the pH range of 4.5 to 7.5. The results showed that the microbicidal activity of synthetic peptide sequences, based on the antimicrobial {alpha}-helix region of LF, can be significantly enhanced by optimizing the length and substitution of neutral amino acids at specific positions, thus suggesting a sequence lead with therapeutic potential.

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