The invention refers to multibasic, N-terminally modified tetrapeptide mimetics with a C-terminal P1-arginine mimetic, methods for their production and use for therapy and prophylaxis of diseases, caused by bacterial pathogens or viruses, as well as for therapy and prophylaxis of diabetes, arteriosclerosis, cancer, Alzheimer's or the onset of obesity, as well as the use of these compounds as inhibitors of the proprotein convertases which cleave behind basic P1 residues, especially for inhibition of the protease furin.