Activities
The modes of action by which antimicrobial peptides kill bacteria is varied and includes disrupting membranes, interfering with metabolism, and targeting cytoplasmic components. The initial contact between the peptide and the target organism is electrostatic, as most bacterial surfaces are anionic, or hydrophobic, such as in the antimicrobial peptide Piscidin. Their amino acid composition, amphipathicity, cationic charge and size allow them to attach to and insert into membrane bilayers to form pores by ‘barrel-stave’, ‘carpet’ or ‘toroidal-pore’ mechanisms. Alternately, they may penetrate into the cell to bind intracellular molecules which are crucial to cell living. Intracellular binding models includes inhibition of cell wall synthesis, alteration of the cytoplasmic membrane, activation of autolysin, inhibition of DNA, RNA, and protein synthesis, and inhibition of certain enzymes. However, in many cases, the exact mechanism of killing is not known. One emerging technique for the study of such mechanisms is dual polarisation interferometry,. In contrast to many conventional antibiotics these peptides appear to be bacteriocidal (bacteria killer) instead of bacteriostatic (bacteria growth inhibitor). In general the antimicrobial activity of these peptides is determined by measuring the minimal inhibitory concentration (MIC), which is the lowest concentration of drug that inhibits bacterial growth.
Read more about this topic: Antimicrobial Peptides
Famous quotes containing the word activities:
“Love and work are viewed and experienced as totally separate activities motivated by separate needs. Yet, when we think about it, our common sense tells us that our most inspired, creative acts are deeply tied to our need to love and that, when we lack love, we find it difficult to work creatively; that work without love is dead, mechanical, sheer competence without vitality, that love without work grows boring, monotonous, lacks depth and passion.”
—Marta Zahaykevich, Ucranian born-U.S. psychitrist. “Critical Perspectives on Adult Women’s Development,” (1980)
“That is the real pivot of all bourgeois consciousness in all countries: fear and hate of the instinctive, intuitional, procreative body in man or woman. But of course this fear and hate had to take on a righteous appearance, so it became moral, said that the instincts, intuitions and all the activities of the procreative body were evil, and promised a reward for their suppression. That is the great clue to bourgeois psychology: the reward business.”
—D.H. (David Herbert)
“If it is to be done well, child-rearing requires, more than most activities of life, a good deal of decentering from one’s own needs and perspectives. Such decentering is relatively easy when a society is stable and when there is an extended, supportive structure that the parent can depend upon.”
—David Elkind (20th century)