N-terminal analogs of pleurocidin-amide, an antimicrobial peptide

Roxanne N LaCroix, University of Rhode Island


We have a problem. We are rapidly running out of effective antibiotics for treating infection, and therefore need a new generation of antibiotics. Many existing natural products exhibit antimicrobial properties, for example, short chain antimicrobial peptides (AMPs) ranging from 20 to 45 amino acids in length. AMPs can be used as models for antibiotics. Pleurocidin amide, a modified version (amidated) of the antimicrobial peptide found in the skin mucous secretions of the winter flounder (Pleuronectes americanus ) is a more active form. Therefore, three other amidated analogs were designed and synthesized for testing as possible antibiotics, searching for one with a higher efficacy than pleurocidin amide. Pleurocidin amide (LM4-12) and new analogs are shown below: LM4-12 N-Ter H-GWGSFFKKAAHVGKHVGKAALTHYL-NH 2C-Ter LM4-13 N-Ter H-WGWGSFFKKAAHVGKHVGKAALTHYL-NH 2C-Ter LM4-14 N-Ter H-GWGWGSFFKKAAHVGKHVGKAALTHYL-NH 2C-Ter LM4-15 N-Ter H-RGWGSFFKKAAHVGKHVGKAALTHYL-NH 2C-Ter ^ Pleurocidin amide and its analogs were synthesized using solid phase peptide synthesis (SPPS) and the split/mix method. The crude peptide was purified initially by Size exclusion chromatography (G25-sephadex resin in a 10% acetic acid solution) and analyzed by UV at target wavelength of 280 nm. Peptides were further purified by reverse phase high-pressure liquid chromatography (RP-HPLC) employing an acetonitrile-water gradient system. Peptides were analyzed for purity by Matrix Assisted Laser Desorption Ionization-Mass Spectrometry (MALDI–MS) using an eight spot gold chip with a sinapinic acid matrix. The purified peptides were tested for antimicrobial efficacy using the high through-put BioAssay against four target human pathogens: Enterococcus faecalis (EF) ATCC: 29212, Escherichia coli (EC) ATCC: 25922, Pseudomonas aeruginosa (PA) ATCC: 27853, Staphylococcus aureus (SA) ATCC: 25923. LM4-15 showed an increased antibiotic efficacy when compared to pleurocidin amide at a concentration of 0.025 ng/ml.^

Subject Area

Chemistry, Biochemistry|Chemistry, Pharmaceutical

Recommended Citation

Roxanne N LaCroix, "N-terminal analogs of pleurocidin-amide, an antimicrobial peptide" (2011). Dissertations and Master's Theses (Campus Access). Paper AAI1490913.