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Antimicrobial activity of synthetic all-D mastoparan M
Abstract:
Mastoparan M, a tetradecapeptide toxin (INKAIAALAKKLL-NH2) from hornet venom and its D-form mastoparan M were synthesized chemically. All D- and L-mastoparan M forms were found to adopt 28% alpha-helical structures in a 30% trifluroethanol solution as shown by the circular dichroism spectrum. All-D mastoparan M caused 3H-thymidine release from labeled bacterial cells after incubation for 1 h and complete cell lysis by 4 h. Both L- and D-mastoparan M showed strong activity against gram-positive and gram-negative bacteria. All-D mastoparan M showed 2-fold higher antibacterial activity than L-mastoparan M. The effects of all-D mastoparan M on the surface morphology of Staphylococcus aureus (ATCC29213) and Escherichia coli (ATCC25922) were studied by scanning-beam electron microscopy. Blast-like bleb extrusions on the surface of some S. aureus and swellings on the end of E. coli were seen after culture with all-D mastoparan M. These findings indicated the all-D mastoparan M could kill bacteria by disrupting cells.
Insights
Chemically synthesized mastoparan M and its D-form exhibit potent antibacterial activity. All-D mastoparan M demonstrates enhanced efficacy, killing bacteria by disrupting cell membranes.
Area of Science:
- Biochemistry
- Microbiology
- Peptide Chemistry
Background:
- Mastoparan M is a tetradecapeptide toxin found in hornet venom.
- Peptide toxins are investigated for their potential antimicrobial properties.
Purpose of the Study:
- To synthesize and characterize L- and D-forms of mastoparan M.
- To evaluate the antibacterial activity and mechanism of action of mastoparan M.
- To compare the efficacy of D-mastoparan M against L-mastoparan M.
Main Methods:
- Chemical synthesis of mastoparan M and its D-form.
- Circular dichroism spectroscopy to determine alpha-helical structure.
- Bacterial cell viability assays (3H-thymidine release).
- Scanning-beam electron microscopy to observe morphological changes.
Main Results:
- Both L- and D-mastoparan M adopt alpha-helical structures in solution.
- All-D mastoparan M induced rapid bacterial cell lysis and showed strong activity against Gram-positive and Gram-negative bacteria.
- All-D mastoparan M exhibited twofold higher antibacterial activity compared to L-mastoparan M.
- Electron microscopy revealed cell surface blebbing and swelling upon treatment with all-D mastoparan M.
Conclusions:
- Mastoparan M, particularly its D-form, possesses significant antibacterial properties.
- The antibacterial mechanism involves disruption of bacterial cell membranes.
- D-mastoparan M represents a promising candidate for antimicrobial development.