Bombinins.

The skin secretion of Bombina species contains antimicrobial peptides with interesting biological properties. These peptides can be grouped into two distinct subfamilies, the bombinin and the bombinin H. The former comprises 27 amino acid residue peptides with a large spectrum of antimicrobial activity but virtually devoid of lytic effect on human erythrocytes. The latter includes 20 or 17 residue hemolytic peptides, some of which contain a D-amino acid in the second position of their sequence, as a result of a posttranslational modification. A brief description of the genes coding for these two peptide families, their biological activities along with the underlying molecular mechanism, are reported. Importantly, the presence of a single D-amino acid substitution represents a new approach naturally developed not only to modulate peptide stability in vivo, but also to confer the all-L peptide and its diastereomer distinctive biological features.