title: Cytotoxic and membrane perturbation effects of a novel amyloid forming model peptide poly(leucine-glutamic acid).
abstract: In the present study we have elucidated the toxicity of a novel amyloid forming model peptide, Poly (leucine-glutamic acid). The toxicity of the fibrils prepared from this peptide was analyzed in peripheral blood lymphocytes (PBL). The MTT reduction assay revealed that the viability of PBL decreases significantly upon treatment with Poly(leucine-glutamic acid) (Poly [LE]). Enhanced DCFH-DA fluorescence in treated cells suggests that peptide toxicity is probably mediated by the formation of free radicals. In vivo and in vitro biochemical studies indicated that Poly [LE] inactivates the antioxidant system of cells. Perturbation of Poly [LE] in a membrane lipid environment was assessed by circular dichroism (CD) using phosphotidyl choline-cholesterol bilayers. The CD results revealed that LE enhances its beta sheet content in a bilayer environment. Sequestration of Poly [LE] in lipid rafts demonstrates that it has a binding cleft similar to Abeta in lymphocyte raft domains. Nuclear membrane binding studies showed that Poly [LE] binds to nuclear membranes and may cause genotoxicity.
authors.affiliation: Bio-organic and Neurochemistry Division, Central Leather Research Institute, Adyar, Chennai 600 020, India. karkuvi77@hotmail.com
authors.forename: Rajadas
authors.initials: R
authors.lastname: Jayakumar
authors.forename: Jayaraman
authors.initials: J
authors.lastname: Murali
authors.forename: Deenadayalan
authors.initials: D
authors.lastname: Koteeswari
authors.forename: Kannayiram
authors.initials: K
authors.lastname: Gomathi
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry; D000682:Amyloid / Q000737:chemistry*; D016229:Amyloid beta-Peptides / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D005609:Free Radicals / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007930:Leucine / Q000031:analogs & derivatives* / Q000737:chemistry; D008051:Lipid Bilayers / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism; D008856:Microscopy, Fluorescence; D010100:Oxygen / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011099:Polyglutamic Acid / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000682:Amyloid; D016229:Amyloid beta-Peptides; D005609:Free Radicals; D008051:Lipid Bilayers; D010455:Peptides; D013778:Tetrazolium Salts; D013844:Thiazoles; C106782:poly(glutamic acid-leucine); D011099:Polyglutamic Acid; D018698:Glutamic Acid; D013482:Superoxide Dismutase; D000251:Adenosine Triphosphatases; C022616:thiazolyl blue; D005978:Glutathione; D007930:Leucine; D010100:Oxygen