A possible target site of 1, 3, 5-triazine nitrification inhibitors
1995
Murakami, M. (Tamagawa Univ., Machida, Tokyo (Japan)) | Takagi, S. | Takahashi, I. | Tokuyama, T. | Sato, Y. | Vonk, J.W. | Wakabayashi, K.
Trichloromethyl-1,3,5-triazines were synthesized and their nitrification inhibitory activity in upland soil was evaluated by measuring pI(50) (soil) values, the negative logarithm of molar I(50) (soil). Furthermore, pI(50) (soil-water) values were calculated using the soil adsorption coefficient. Measurement of accumulated nitrification intermediates, NH2OH and NO2(-)-N, revealed a possibility that the nitrite formation step was blocked by the triazine inhibitors. The active triazines inhibited ammonia-oxidation step, but did not inhibit hydroxylamineoxidation step in Nitrosomonas europaea ATCC 25978. The formers inhibitory indices were expressed as pI(50) (cell suspension) values. These results suggest that the target enzyme of 1,3,5-triazine nitrification inhibitors may be the ammonia monooxygenase in N, europaea ATCC 25978. In addition, a good correlation was found between the three types of pI(50)-values and hydrophobic parameter, log P, by quantitative structure activity relationship. The optimum log P values in the three equations obtained using pI(50) (soil), pI(50) (soil-water) and pI(50) (cell suspension) values, were calculated as 2.65, 5.03 and 5.04, respectively
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