The invention relates to a peptide or peptide derivative having the general formula: Sub1-X1-D2K3-P4-P5-Y6-L7-P8-R9-P10-X2-P12-P13-R14-X3-I16-P17/Y17-N18-N19-X4-Sub2, wherein X1 is a non-polar, hydrophobic group or a positively charged group, D2 is asparagine or glutamine, K3, X2, and X4 are positively charged groups, X3 is a positively charged group, proline, or a proline derivative; L7 and I16 are non-polar, hydrophobic groups, Y6 and Y17 are tyrosine, R9 and R14 are arginine, N18 and N19 are asparagine or glutamine, P4, P5, P8, P10, P12, P13, and P17 are proline, hydroxyproline, or derivatives thereof, wherein possibly one or two of the groups selected from D2, P4, P5, P8, P10, P12, P13, P17, and Y17 are replaced by an arbitrary group and/or P13 and R14 are exchanged, Sub1 is the free or modified N-terminus, and Sub2 is the free or modified C-terminus. The invention further relates to the use of the peptides and peptide derivatives in medicine, as an antibiotic, in a disinfectant or cleaning agent, as a preservative or in a packaging material, in pharmaceutical research, or in a screening method.