title: Improving the antibacterial activity and selectivity of an ultra short peptide by hydrophobic and hydrophilic amino acid stretches.
abstract: The principle of amino acid stretches tagged at the C terminal of Luecrocin I, which is an ultra-short antibacterial peptide, by tryptophan and arginine or lysine has been reported. The choice of amino acid type at each stretch position depends on the hydrophobic and hydrophilic regions visualized in the helical wheel pattern of Luecrocin I. Oligopeptide tagging should also consider the properties such as positive charge, hydrophobicity, the content of hydrophobic amino acids, polar angle, the properly hydrophilic and hydrophobic facets. Amidation at C terminal and lysine substitute for arginine can increase selectivity between mammalian cells (hemolytic and MTT assay) and bacterial cells tested. KT2 and RT2 which have 53% hydrophobic residues, 7 positive charges, 160° polar angle, -0.02 (KT2) and -0.04 (RT2) hydrophobicity were effective against S. typhi DMST 22842, S. epidermidis ATCC 12228, E. coli ATCC 25922 and V. cholerae non-O1, non-O139. The SEM images implied that the antibacterial mechanism of RT2 and KT2 may depend on concentration rather than time. Finally, RT2 and KT2 can be new antibacterial agents or may be further developed for alternative antibiotics.
authors.affiliation: Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Thitiporn
authors.initials: T
authors.lastname: Anunthawan
authors.forename: Nualyai
authors.initials: N
authors.lastname: Yaraksa
authors.forename: Santi
authors.initials: S
authors.lastname: Phosri
authors.forename: Tinnakorn
authors.initials: T
authors.lastname: Theansungnoen
authors.forename: Sakda
authors.initials: S
authors.lastname: Daduang
authors.forename: Apisak
authors.initials: A
authors.lastname: Dhiravisit
authors.forename: Sompong
authors.initials: S
authors.lastname: Thammasirirak
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D015195:Drug Design; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D012485:Salmonella typhi / Q000187:drug effects*
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D010455:Peptides
keywords: Helical wheel; Hydrophilic facets; Hydrophobic facets; Luecrocin I; Peptide design