Related Experiment Video
Updated: Jul 19, 2026
Production and Testing of Antimicrobial Peptides and Their Mimics
Published on: April 10, 2026
Improvement of bacterial cell selectivity of melittin by a single Trp mutation with a peptoid residue
Wan Long Zhu1, Yoonkyung Park, Il-Seon Park
1Department of Bio-Materials, Graduate School and Research Center for Proteineous Materials, Chosun University, Gwangju 501-759, Korea.
Abstract:
To design melittin (ME) analogues that are not cytotoxic against mammalian cells but which possessing potent antimicrobial activity, we synthesized a ME analogue (ME-w) in which the Trp-19 residue of ME was replaced by a Trp-peptoid residue (Nhtrp). ME-w exhibited similar antimicrobial activity compared to ME against the tested six bacteria and C. albicans. However, it was much less cytotoxic against the hRBCs and HeLa and NIH-3T3 cells than ME. Tryptophan fluorescence and CD spectra revealed that the Trp-19 --> Nhtrp substitution in ME contributed to a much lower helical assembly in an aqueous environment and structural flexibility and exterior localization to zwitterionic membrane which modulates its selectivity toward bacterial cells.
Insights
Researchers designed a melittin (ME) analogue, ME-w, by replacing a key residue. This modified peptide retains potent antimicrobial activity while significantly reducing cytotoxicity against mammalian cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Melittin (ME), a primary component of bee venom, exhibits potent antimicrobial properties.
- However, its significant cytotoxicity against mammalian cells limits its therapeutic applications.
- Developing ME analogues with preserved antimicrobial efficacy and reduced host cell toxicity is crucial.
Purpose of the Study:
- To design and synthesize a novel melittin (ME) analogue (ME-w) with reduced cytotoxicity.
- To evaluate the antimicrobial activity and cytotoxicity of ME-w compared to native ME.
- To elucidate the structural basis for the improved selectivity of ME-w.
Main Methods:
- Synthesis of a melittin analogue (ME-w) by substituting the Trp-19 residue with a Trp-peptoid residue (Nhtrp).
- Antimicrobial activity assays against six bacterial species and Candida albicans.
- Cytotoxicity assays using human red blood cells (hRBCs), HeLa, and NIH-3T3 cells.
- Structural analysis using tryptophan fluorescence and circular dichroism (CD) spectroscopy.
Main Results:
- ME-w demonstrated comparable antimicrobial activity to native ME against tested bacteria and C. albicans.
- ME-w exhibited significantly lower cytotoxicity against hRBCs, HeLa, and NIH-3T3 cells compared to ME.
- Structural studies indicated that the Trp-19 --> Nhtrp substitution reduced helical assembly in aqueous environments.
- This substitution also enhanced structural flexibility and exterior localization to zwitterionic membranes, improving selectivity.
Conclusions:
- The synthesized ME-w analogue effectively retains potent antimicrobial activity while exhibiting markedly reduced mammalian cell cytotoxicity.
- The structural modifications, specifically the Trp-19 to Nhtrp substitution, are responsible for the enhanced selectivity of ME-w towards bacterial cells.
- ME-w represents a promising candidate for developing safer and more effective antimicrobial agents derived from melittin.
