Abstract
Four AS-48 mutants (Trp24Ala, Gly13Lys, Leu40Lys and Ala53Ser) were obtained by site-directed mutagenesis. The minimal inhibitory concentration of each peptide showed that only residue Trp24 was unquestionably involved in the biological activity. Guanidine hydrochloride-induced unfolding assays showed a three-state transition denaturation process, suggesting a molten-globule-like conformation after the first transition.
Keywords: Circular antimicrobial peptides, site-directed mutagenesis, lactic-acid bacteria, enterococci