|AMP > Introduction > Proposed
mechanism of action of cationic peptides:
In spite of the fact that the mechanism of action is not satisfactory established for all cationic peptides, the structural model established by Shai-Matzusaki-Huang provides a reasonable explanation for most antimicrobial activities of these compounds (Zasloff, 2002). The model proposes that these linear amphipatic-helical peptides interact with bacterial membranes and increase their permeability, either by the effect of their positive charges with anionic lipids of the target membrane or by membrane destabilization through lipid displacements due to the drastic changes in the net charge of the composed system. A similar mechanism has been proposed for the cysteine-rich peptides such as defensins, which are suggested to form ion-permeable channels in the lipid bilayer. In contrast, some peptides penetrate into cells to exert their action over target molecules . Several additional hypotheses have been proposed to explain the mechanisms by which peptides kill target cells; such hypotheses include induction of hydrolases which degrade the cell wall, disturbance of membrane functions and damage to crucial intracellular targets after internalization of the peptide .
Anionic peptides: This is a smaller novel group of molecules displaying antimicrobial activity which, up to now, have been mostly isolated from mammals.
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