Magainins cells

Melittin, a 26-amino acid amphipathic a-helical peptide that occurs in bee venom, has recently been found capable of suppressing HIV-1 gene expression. Melittin inhibits HIV-1 infection in both acutely and persistently infected t-lymphoma (KE37/1) and fibroblastoid (LC5) cells at an IC50 of 0.5 to 1.5 iM this effect is apparently mediated by a direct suppressive action on the HIV long terminal repeat (LTR). Antimicrobial peptides such as melittin (honeybees), cecropin (moths), and magainin (frogs) may thus inhibit cell-associated HIV-1 production at the transcription level. 

Another kind of contact-active antimicrobial surface was achieved by tethering antimicrobial peptides to surfaces [62], If such peptides were exclusively membrane-active they could not work like in solution but would be immobilized via a polymeric spacer that could potentially cross the cell wall. The latter was demonstrated by the group of Dathe, who immobilized cationic antimicrobial peptides on PentaGels [63], Also, the well-known antimicrobial peptide magainin I... 

There are other types of spikes on the skin. One of the most interesting is a class of molecules called magainins, discovered by a biologist named Mike Zasloff after he wondered why live laboratory frogs that are cut open and sewed back up in nonsterile conditions rarely get infections. He showed that their skin excretes a substance which can kill bacterial cells since then, magainins have been discovered in many kinds of animals. But magainins, like the RNA-destroying enzymes, are not precursors to the sophisticated defense systems under the skin of animals. 

Takeshima, K., Chikushi, A., Lee, K. K., Yonehara, S., and Matsuzaki, K. (2003) Translocation of analogues of the antimicrobial peptides magainin and buforin across human cell membranes. J. Biol. Chem. 278, 1310-1315. 

Although historically most useful antibiotics have come from spore forming microorganisms, marine organisms have yielded the candidate antitumor peptide didemnin B [77327-50-0] (2) and cytostatic peptides such as the patellamides (3). Many of the marine peptides have little or no antimicrobial activity. Antibacterial peptides called magainins are found in frog skin (4) and antibacterial proteins called defensins are found in mammalian white blood cells (5). The commercially important insecticidal proteins from Bacillus thuringensis (6) are not discussed herein nor are the numerous peptide siderophores (7,8), which, except for the albomycins (9), are usually not antimicrobial. 

Dr. Zasloff found two molecules in frog skin that can kill bacteria. Both are small proteins. Zasloff named them magainins, from the Hebrew word for shield. Most of the antibiotics that we now use enter bacteria and kill them by stopping some biochemical process inside the cell. Magainins are more direct they simply punch holes in the bacterial membrane, and the bacteria explode. 

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