Amy Won
Carleton University
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Publication
Featured researches published by Amy Won.
Biochimica et Biophysica Acta | 2009
Amy Won; Anatoli Ianoul
Comparative studies of the effect of a short synthetic cationic peptide, pEM-2 (KKWRWWLKALAKK), derived from the C-terminus of myotoxin II from the venom of the snake Bothrops asper on phospholipid mono- and bilayers were performed by means of Langmuir Blodgett (LB) monolayer technique, atomic force microscopy and calcein leakage assay. Phospholipid mono- and bilayers composed of single zwitterionic or anionic phospholipids as well as lipid mixtures mimicking bacterial cell membrane were used. LB measurements indicate that the peptide binds to both anionic and zwitterionic phospholipid monolayers at low surface pressure but only to anionic at high surface pressure. Preferential interaction of the peptide with anionic phospholipid monolayer is also supported by a more pronounced change of the monolayer pressure/area isotherms induced by the peptide. AFM imaging reveals the presence of nanoscale aggregates in lipid/peptide mixture monolayers. At the same time, calcein leakage experiment demonstrated that pEM-2 induces stronger disruption of zwitterionic than anionic bilayers. Results of the study indicate that electrostatic interactions play a significant role in the initial recognition and binding of pEM-2 to the cell membrane. However, membrane rupturing activity of the peptide depends on interactions other than simple ionic attraction.
Biochimica et Biophysica Acta | 2011
Amy Won; Mourin Khan; Sorin Gustin; Akuvi Akpawu; Deeptee Seebun; Tyler J. Avis; Bonnie O. Leung; Adam P. Hitchcock; Anatoli Ianoul
Isolated from the venom sac of solitary spider wasp, Anoplius samariensis, anoplin is the smallest linear α-helical antimicrobial peptide found naturally with broad spectrum activity against both Gram-positive and Gram-negative bacteria, and little hemolytic activity toward human erythrocytes. Deamidation was found to decrease the peptides antibacterial properties. In the present work, interactions of amidated (Ano-NH2) and deamidated (Ano-OH) forms of anoplin as well as Ano-NH2 composed of all D-amino acids (D-Ano-NH2) with model cell membranes were investigated by means of Langmuir Blodgett (LB) technique, atomic force microscopy (AFM), X-ray photoemission electron microscopy (X-PEEM) and carboxyfluorescein leakage assay in order to gain a better understanding of the effect of these peptide modifications on membrane binding and lytic properties. According to LB, all three peptides form stable monolayers at the air/water interface with Ano-NH2 occupying a slightly greater area per molecule than Ano-OH. All three forms of the peptide interact preferentially with anionic 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DPPG), rather than zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayer. Peptides form nanoscale clusters in zwitterionic but not in anionic monolayers. Finally, membrane lytic activity of all derivatives was found to depend strongly on membrane composition and lipid/peptide ratio. The results suggest that amidated forms of peptides are likely to possess higher membrane binding affinity due to the increased charge.
Biophysical Journal | 2012
Amy Won; Annamaria Ruscito; Anatoli Ianoul
Latarcin 2a (ltc2a, GLFGKLIKKFGRKAISYAVKKARGKH-COOH) is one of the seven short linear antimicrobial and cytolytic peptides extracted from the venom of the Central Asian spider, Lachesana tarabaevi, with lytic activity against Gram-positive and Gram-negative bacteria, erythrocytes, and yeast at micromolar concentrations. Ltc2a is known to adopt helix-hinge-helix conformation in membrane mimicking environment, whereas its derivative latarcin 2aG11A (ltc2aG11A, GLFGKLIKKFARKAISYAVKKARGKH-COOH), likely adopts a more rigid helical structure, has higher nonspecific interaction with zwitterionic membrane and is potentially more toxic against eukaryotic cells. In this work, interactions of two ltc2a derivatives with supported lipid bilayers (DOPC/egg SPM/Chol 40/40/20 mol%) were studied by in situ atomic force microscopy. Interactions are affected by membrane fluidity and peptide concentration. Both peptides induced reorganization of raft model membrane by reducing line tension of the liquid ordered phase. Ltc2aG11A-induced raft membrane thinning may be due to membrane interdigitation. Presence of cholesterol was determined to be important to attenuate peptide induced membrane disruption. Finally, leakage assay showed both peptides have similar membrane permeability toward various model membrane vesicles.
Biophysical Journal | 2010
Grace Idiong; Amy Won; Stahs Pripotnev; Anatoli Ianoul
Latarcins are linear antimicrobial peptides purified from the venom of the Lachesana tarabaevi spider. They are highly active against Gram-positive and Gram-negative bacteria with minimum inhibitory concentrations (MIC) at the micromolar level and low hemolytic activity (1, 2). In the present work, a 26 residue peptide Latarcin 2a that adopts a helix-hinge-helix conformation in a membrane mimetic environment (1, 2) was studied as well as a derivative obtained by replacing the Guanine 11 by with Alanine. The interaction of the peptides with phospholipid mono and bilayers were investigated using Langmuir-Blodgett monolayer technique, Atomic Force Microscopy (AFM), calcein leakage assay and UV resonance Raman spectroscopy. Effect of small changes in the primary structure of the peptide on the membrane rupturing activity is discussed.References:1. Kozlov, S.A.; Vassilevski, A.A.; Feofanov, A.V.; Surovoy, A.Y.; Karpunin, D.V.; Grishin E.V. J. Biol. Chem. 2006, 281, 20983-20992;2. Dubovskii, P.V.; Volynsky, P.E.; Polyanski, A.A.; Chupin, V.V.; Efremov, R.G.; Arseniev, A.S. Biochemistry 2006, 45, 10759-10767.
Journal of Physical Chemistry B | 2011
Amy Won; Stahs Pripotnev; Annamaria Ruscito; Anatoli Ianoul
European Biophysics Journal | 2011
Grace Idiong; Amy Won; Annamaria Ruscito; Bonnie O. Leung; Adam P. Hitchcock; Anatoli Ianoul
Biochimica et Biophysica Acta | 2012
Amy Won; Annamaria Ruscito; Anatoli Ianoul
European Biophysics Journal | 2011
Bonnie O. Leung; Adam P. Hitchcock; Amy Won; Anatoli Ianoul; Andreas Scholl
Journal of Raman Spectroscopy | 2010
Stahs Pripotnev; Amy Won; Anatoli Ianoul
Biophysical Journal | 2010
Amy Won; Mourin Khan; Sorin Gustin; Akuvi Akpawu; Stahs Pripotnev; Anatoli Ianoul