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What are some substances toxic to all eukaryotes but not to most prokaryotes?

  1. Aug 8, 2011 #1


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    Some examples I thought about: cyanide, carbon monoxide (although it isn't as toxic to plants as it is to animals), and anything else that disrupts mitochondrial function (though it must be remembered that mitochondria are related to many bacteria)

    One suggestion I thought of: what about things that can penetrate the cell membranes of all organisms with a single cell membrane, but might not be able to penetrate the two cell membranes of gram-negative bacteria? Do such substances exist?

    PS: I was discussing this issue with NASA Astrobiologist Chris McKay, so any responses would be interesting to him as well.
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  3. Aug 8, 2011 #2


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    Cyanide would also likely be toxic to aerobic bacteria since cyanide targets cytochrome c oxidase and bacteria also use this enzyme in their electron transport chain.

    Thinking about drugs that can penetrate only a single cell membrane but not two cell membranes is a good idea, but I don't know of any drugs with that property.

    Some good eukaryote-specific drug targets would include things like nuclear import/export, membrane trafficking, and the cytosketon. For example, taxol inhibits microtubules which are required for cell division in eukaryotes (animals and fungi at least, I'm not 100% sure about plants and protists), but not in prokaryotes.

    In theory, it should also be possible to develop compounds that specifically inhibit some enzymes in animals or plants but not bacteria. For example, researchers have discovered a number of compounds that inhibit bacterial ribosomes but not animal ribosomes. Since these drugs rely on the subtle differences between the structures of animal and bacterial ribosomes, it should be possible to screen for or maybe even design molecules that would inhibit animal ribosomes but not bacterial ribosomes (of course, it would require a lot of work to design, synthesize, and test these compounds. I presume you're looking for compounds that are commercially available). Also, one would likely need a cocktail of these compounds (e.g. the animal-specific ribosomal inhibitor might not work against fungi or plants, so you might have to design a fungi-specific and plant-specific ribosomal inhibitors as well)

    May I ask what for what application are you planning to use these compounds? It sounds like you have some interesting ideas for experiments planned.
    Last edited: Aug 8, 2011
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