title: Immobilization and orientation-dependent activity of a naturally occurring antimicrobial peptide.
abstract: A naturally occurring antimicrobial peptide, SMAP-29, was synthesized with an n-terminal or c-terminal cysteine, termed c_SMAP and SMAP_c, respectively, for site-directed immobilization to superparamagnetic beads. Immobilized SMAP orientation-dependent activity was probed against multiple bacteria of clinical interest including Acinetobacter baumannii, Pseudomonas aeruginosa, Bacillus anthracis sterne and Staphylococcus aureus. A kinetic microplate assay was employed to reveal both concentration and time-dependent activity for elucidation of minimum bactericidal concentration (MBC) and sub-lethal effects. Immobilized SMAP activity was equivalent or reduced compared with soluble SMAP_c and c_SMAP regardless of immobilization orientation, with only one exception. A comparison of immobilized SMAP_c and c_SMAP activity revealed a bacteria-specific potency dependent on immobilization orientation, which was contrary to that seen in solution, wherein SMAP_c was more potent against all bacteria than c_SMAP. Sub-MBC kinetic studies displayed the influence of peptide exposure to the cells with multiple bacteria exhibiting increased susceptibility and efficacy at lower concentrations upon extended exposure (i.e. MBC enhancement). For instances in which complete killing was not achieved, two predominant effects were evident: retardation of growth rate and an increased lag phase. Both effects, seen independently and concomitantly, indicate some degree of induced cellular damage that can serve as a predictor toward eventual cell death. SMAP_c immobilized on glass through standard silanization chemistry was also investigated to ascertain the influence of substrate on activity against select bacteria.
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, 01760, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Soares
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, 01760, USA.
authors.forename: Romy
authors.initials: R
authors.lastname: Kirby
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, 01760, USA.
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Doherty
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, 01760, USA.
authors.forename: Alexa
authors.initials: A
authors.lastname: Meehan
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, 01760, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Arcidiacono
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D001408:Bacillus anthracis / Q000187:drug effects; D001798:Blood Proteins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D054804:Cathelicidins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D003545:Cysteine / Q000737:chemistry; D055767:Immobilized Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D008826:Microbial Sensitivity Tests / Q000379:methods; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001798:Blood Proteins; D054804:Cathelicidins; D055767:Immobilized Proteins; C403305:SMAP29 protein, Ovis aries; D003545:Cysteine
keywords: activity; antimicrobial; immobilized; peptide