title: Conformational and functional studies of gomesin analogues by CD, EPR and fluorescence spectroscopies.
abstract: The aim of this work was to examine the bioactivity and the conformational behavior of some gomesin (Gm) analogues in different environments that mimic the biological membrane/water interface. Thus, manual peptide synthesis was performed by the solid-phase method, antimicrobial activity was evaluated by a liquid growth inhibition assay, and conformational studies were performed making use of several spectroscopic techniques: CD, fluorescence and EPR. [TOAC(1)]-Gm; [TOAC(1), Ser(2,6,11,15)]-Gm; [Trp(7)]-Gm; [Ser(2,6,11,15), Trp(7)]-Gm; [Trp(9)]-Gm; and [Ser(2,6,11,15), Trp(9)]-Gm were synthesized and tested. The results indicated that incorporation of TOAC or Trp caused no significant reduction of antimicrobial activity; the cyclic analogues presented a beta-hairpin conformation similar to that of Gm. All analogues interacted with negatively charged SDS both above and below the detergent's critical micellar concentration (cmc). In contrast, while Gm and [TOAC(1)]-Gm required higher LPC concentrations to bind to micelles of this zwitterionic detergent, the cyclic Trp derivatives and the linear derivatives did not seem to interact with this membrane-mimetic system. These data corroborate previous results that suggest that electrostatic interactions with the lipid bilayer of microorganisms play an important role in the mechanism of action of gomesin. Moreover, the results show that hydrophobic interactions also contribute to membrane binding of this antimicrobial peptide.
authors.affiliation: Department of Biophysics, Federal University of São Paulo, Rua 03 de Maio, 100, 04044-020, São Paulo, SP, Brazil.
authors.forename: Luis G M
authors.initials: LG
authors.lastname: Moraes
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Fázio
authors.forename: Renata F F
authors.initials: RF
authors.lastname: Vieira
authors.forename: Clovis R
authors.initials: CR
authors.lastname: Nakaie
authors.forename: M Terêsa M
authors.initials: MT
authors.lastname: Miranda
authors.forename: Shirley
authors.initials: S
authors.lastname: Schreier
authors.forename: Sirlei
authors.initials: S
authors.lastname: Daffre
authors.forename: Antonio
authors.initials: A
authors.lastname: Miranda
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D001410:Bacillus megaterium / Q000187:drug effects / Q000254:growth & development; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects*; D002942:Circular Dichroism; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry; D008823:Micelles; D008826:Microbial Sensitivity Tests; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013113:Spin Labels; D013329:Structure-Activity Relationship; D014364:Tryptophan / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D003497:Cyclic N-Oxides; D008051:Lipid Bilayers; D008563:Membrane Lipids; D008823:Micelles; D013113:Spin Labels; C415987:gomesin; D014867:Water; D014364:Tryptophan; C037109:2,2,6,6-tetramethylpiperidine-N-oxide-4-amino-4-carboxylic acid