Effects of Structure of Active Compounds on Biological Activity and Specificity
It is probable that the chemical basis of resistance and specificity will be found in part from studies of the interactions of toxins with plants susceptible and resistant to those toxins. The Phytotoxins with the most selective toxicity are the host-specific toxins; these are much more active in altering the metabolism of host plants susceptible to the toxin-producing micro-organism. Many host-specific toxins are unusually potent causing biological effects at concentrations less than 10-10 g/ml. The specificity and potency of these toxins suggest that they efficiently inhibit important biochemical processes in susceptible plants. Resistant plants either lack these pathways or possess mechanisms that protect against the action of the toxin. Elucidation of these resistance mechanisms will greatly increase our knowledge of specificity. Unfortunately the instability and chemical complexity of certain host-specific toxins have complicated mechanism of action studies because of uncertainties about chemical purity and concentration and by making structure determinations very difficult.
KeywordsDihydrofolate Reductase Selective Toxicity Compound XVII Full Biological Activity Cyclic Tetrapeptide
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