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Soil Science Society of America Journal Abstract -

Inhibition of Urease Activity by Heterocyclic Sulfur Compounds1


This article in SSSAJ

  1. Vol. 42 No. 1, p. 66-72
    Received: May 6, 1977
    Accepted: Sept 15, 1977

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  1. W. D. Gould,
  2. F. D. Cook and
  3. J. A. Bulat2



The inhibition of both jack bean urease and soil urease by several heterocyclic mercaptans was investigated. The following compounds not previously tested as urease inhibitors were found to be effective inhibitors of jack bean urease: 1,3,4-thiadiazole-2,5-dithiol; 5-mercapto-3-phenyl-1,3,4-thiadiazole-2-thione; and 5-amino-1,3,4-thiadiazole-2-thiol. The disulfides of the latter two compounds were found to be very potent inhibitors of jack bean urease. The results are consistent with an inhibition mechanism involving a thiol-disulfide exchange reaction between a disulfide and one or more of the sulfhydryl groups of urease. The results also imply that inhibition of urease by the heterocyclic mercaptans was due to trace amounts of the corresponding disulfides or polysulfides in the mercaptan preparations. A number of heterocyclic mercaptans, two disulfides, and a number of known urease inhibitors were evaluated as soil urease inhibitors, and the following compounds were the most effective: 1,4-benzoquinone ∼ hydroquinone > 2,5-dimethyl-1,4-benzoquinone ∼ catechol ∼ 1,3,4-thiadiazole-2,5-dithiol ∼ 2,6-dimethyl-1,4-benzoquinone.

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