The novel BTM-P1 peptide interferes with energetic processes in mitochondria; its antimicrobial activity against Gram-positive and Gram-negative bacteria is described here. BTM-P1 three-dimensional structure was determined by H-1 NMR to explain its biological mechanisms and membrane activity. Structural data indicated that BTM-P1 can form an alpha-helix; circular dichroism analysis confirmed the pepticle's propensity to behave as a typical transmernbrane helix in a lipidic environment. According to the structural characteristics of the polycationic BTM-P1 peptide so revealed, its biological activity can be explained by a mechanism involving the formation of ion-permeable channels in biomembranes. (c) 2006 Elsevier Inc. All rights reserved.