Antimicrobial activity of synthetic all-D mastoparan M

Mastoparan hi, a tetradecapeptide: toxin (INKAIAALAKKLL-NH2) from hornet ve nom and its D-form mastoparan M were synthesized chemically. All D- and L-m astoparan hi 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 H-3-thymidine release from labeled bacterial cells a fter incubation for 1 h and complete cell lysis by 4 h. Both L- and D-masto paran M showed strong activity against Gram-positive and Gram-negative bact eria. All-D mastoparan hi showed 2-fold higher antibacterial activity than L-mastoparan M. The effects of all-D mastoparan hi on the surface morpholog y of Staphylococcus aureus (ATCC29213) and Escherichia coli (ATCC25922) wer e 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 s een after culture with all-D mastoparan M. These findings indicated the all -D mastoparan hi could kill bacteria by disrupting cells. (C) 2000 Publishe d by Elsevier Science B.V. and International Society of Chemotherapy. All r ights reserved.