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A synthetic antimicrobial peptidomimetic (LTX 109): stereochemical impact on membrane disruption

Johan Isaksson1, Bjørn O Brandsdal, Magnus Engqvist

  • 1Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.

Journal of Medicinal Chemistry
|July 8, 2011
PubMed

Insights

Stereochemistry significantly impacts the antimicrobial activity of LTX 109, a synthetic antimicrobial peptidomimetic (SAMP). Optimized stereoisomers show preorganized membrane insertion, while others require energy to penetrate lipid bilayers.

Area of Science:

  • Medicinal Chemistry
  • Biophysics
  • Microbiology

Background:

  • Multidrug-resistant bacterial infections pose a significant global health threat.
  • Synthetic antimicrobial peptidomimetics (SAMPs) like LTX 109 are promising therapeutic agents.
  • Understanding structure-activity relationships is crucial for optimizing antimicrobial efficacy.

Purpose of the Study:

  • To synthesize and evaluate all eight stereoisomers of LTX 109.
  • To investigate the influence of stereochemistry on antimicrobial activity, hemolysis, and hydrophobicity.
  • To elucidate the three-dimensional structures and membrane interaction mechanisms of LTX 109 stereoisomers.

Main Methods:

  • Synthesis of all eight stereoisomers of LTX 109.
  • Antimicrobial susceptibility testing and hemolysis assays.
  • Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations in aqueous and lipid bilayer environments.

Main Results:

  • A strong and unusual dependence of antimicrobial activity on stereochemistry was observed.
  • The most active stereoisomers exhibited preorganized structures for membrane insertion.
  • Less active stereoisomers required an energy penalty for membrane penetration, influenced by improved water solubility via guanidyl-π stacking.

Conclusions:

  • Stereochemistry is a critical determinant of LTX 109's antimicrobial mechanism and efficacy.
  • Structural preorganization significantly enhances membrane insertion and activity.
  • Molecular insights guide the rational design of novel peptidomimetic antibiotics.

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