title: Multiple functions of short synthetic enantiomeric peptides based on beetle defensins.
abstract: Four enantiomeric 9-mer peptides, D-peptides A (RLYLRIGRR-NH(2)), B (RLRLRIGRR-NH(2)), C (ALYLAIRRR-NH(2)), and D (RLLLRIGRR-NH(2)), were designed and synthesized on the basis of a beetle defensin antimicrobial peptide. These D-9-mer peptides have been reported to exhibit multiple functions, including antimicrobial and antiprotozoan activity, without cytotoxicity on normal fibroblasts and leukocyte cells. In this study, we found that the D-9-mer peptides inhibited telomerase activity (IC(100) = 40 microM). A new peptide, D-peptide C2 (ALYLAIRRRRRRRR-NH(2)), designed from D-peptide C to translocate into the cytoplasm by a penetrating sequence (octa-arginine), showed extremely strong telomerase inhibitory activity (IC(100) = 0.1 microM). D-Peptide C2 exhibited a great increase in cytotoxicity against various cancer cell lines (IC(50) = 3.4-26.4 microM). However, the immediate death of the cells suggested that the high cytotoxicity was not an effect of telomerase inhibitory activity. Mitochondrial swelling assay and microscopical observations of mitochondria indicated that the major target of the D-peptide C2 was the mitochondrial membrane.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Jun
authors.initials: J
authors.lastname: Ishibashi
authors.forename: Masanori
authors.initials: M
authors.lastname: Kubo
authors.forename: Demar
authors.initials: D
authors.lastname: Taylor
authors.forename: Minoru
authors.initials: M
authors.lastname: Yamakawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D001517:Coleoptera / Q000737:chemistry*; D023082:Defensins / Q000737:chemistry*; D015195:Drug Design; D006801:Humans; D020128:Inhibitory Concentration 50; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008854:Microscopy, Electron; D008933:Mitochondrial Swelling / Q000187:drug effects; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D012235:Rhodamines / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism; D019098:Telomerase / Q000037:antagonists & inhibitors
chemical_list: D023082:Defensins; D009842:Oligopeptides; D012235:Rhodamines; D019098:Telomerase