Almost all hemolytic and
antimicrobial peptides form part of the defense mechanism of species widely distributed across the evolutionary scale. Although these
peptides are of varying lengths and composition, they form amphiphilic structures in a hydrophobic environment. They also have the ability to form channels in natural and model membranes. Hemolytic
peptides have proven to be very useful in studying the mechanism of
hemolysis and the permeability properties of red blood cells. Preliminary investigations indicate that these
peptides may also be useful in the investigation of complex cellular phenomena like exocytosis and neurotransmission. Although molecules like
vancomycin,
bacitracin and
penicillins have been extensively used as
antibiotics for therapeutic purposes, most species throughout the evolutionary scale use
peptides as
antimicrobial agents. These
peptides exert their activity by altering the permeability properties of the bacterial plasma membrane and do not interfere with macro molecular synthesis like the other
antibiotics that are presently used in
therapies. Hence it is likely that resistance to
peptide antibacterial agents may not develop easily. Since the problem of antibiotic resistance is presently a particularly severe one,
peptide antibiotics may be the drugs of choice in the future.