Alamethicin

Alamethicin is a peptide antibiotic produced by the fungus Trichoderma viride. It belongs to the alamethicin family, a group of linear, amphipathic 20-amino-acid peptides originally isolated from fungal culture filtrates. Natural variants include alamethicin F1 through F6, which differ slightly in sequence and potency.

Chemically, alamethicin is a short, hydrophobic peptide that adopts an alpha-helix conformation in membranes. In lipid bilayers, it inserts and oligomerizes to form voltage-dependent, barrel-stave type channels, leading to ion leakage and membrane depolarization. Channel formation is influenced by membrane composition, cholesterol content, and applied voltage; overall, alamethicin shows higher activity in certain lipid environments.

Biosynthesis occurs via nonribosomal peptide synthetases in Trichoderma species, and the peptide is secreted into the culture medium. Alamethicin exhibits broad-spectrum antimicrobial activity, particularly against fungi and some bacteria, by disrupting membrane integrity. Because of its cytotoxicity and non-specific action, alamethicin is not used clinically but is widely employed in membrane biology and biophysics as a model pore-forming peptide and ion channel former.

Safety and handling: it is a toxin; appropriate laboratory containment and protective equipment are required. In research contexts, alamethicin remains a valuable tool for studying peptide–membrane interactions, channel conductance, and the biophysics of pore formation.