排序方式: 共有3条查询结果,搜索用时 2 毫秒
1
1.
G. A. Rodgers 《Plant and Soil》1984,79(1):155-157
Summary The effect on soil urease activity of five aminocresols, at concentrations of 5–100 g/g soil, was examined in the laboratory. Two compounds, 4-amino-o-cresol and 4-amino-m-cresol, significantly inhibited urease activity. The efficacy of 4-amino-o-cresol was compared with that of phenylphosphorodiamidate (PPDA), a known inhibitor, in three U.K. soils. At 50g/g soil 4-amino-o-cresol was as inhibitory as an equivalent concentration of PPDA in a soil with low urease activity, but was less inhibitory in two soils with high urease activity. 相似文献
2.
Summary In order to improve nitrogen recovery by rice, the effect of a urease inhibitor phenylphosphorodiamidate (PPD) on the efficiency
of fertilizer urea was studied in laboratory and greenhouse. Addition of PPD to urea (5% w/w) delayed urea hydrolysis by 3
to 4 days and reduced ammonia volatilization from 45% (without PPD) to 8.5% (with PPD). Ammonia volatilization obeyed first
order kinetics. Urea hydrolysis was sufficiently strongly inhibited to match the nitrification potential of the soil. N application
to rice by three different modes showed that a delayed mode (4 splits) was superior to two conventional modes (3 splits) in
nitrogen recovery and fertilizer efficiency since it met nitrogen requirement of plants at reproductive stage. In 2 out of
3 modes of application, there was a 14% increase (relative) in grain yields and dry matter, and 6.8% increase in N uptake
efficiency on application of PPD along with urea. The results indicate that urease inhibitors like PPD can be effectively
used to block urea hydrolysis, reduce ammonia volatilization losses and improve N use efficiency by rice. 相似文献
3.
Jack bean urease: the effect of active-site binding inhibitors on the reactivity of enzyme thiol groups 总被引:2,自引:0,他引:2
In view of the complexity of the role of the active site flap cysteine in the urease catalysis, in this work we studied how the presence of typical active-site binding inhibitors of urease, phenylphosphorodiamidate (PPD), acetohydroxamic acid (AHA), boric acid and fluoride, affects the reactivity of enzyme thiol groups, the active site flap thiol in particular. For that the inhibitor-urease complexes were prepared with excess inhibitors and had their thiol groups titrated with DTNB. The effects observed were analyzed in terms of the structures of the inhibitor-urease complexes reported in the literature. We found that the effectiveness in preventing the active site cysteine from the modification by disulfides, varied among the inhibitors studied, even though they all bind to the active site. The variations were accounted for by different extents of geometrical distortion in the active site that the inhibitors introduced upon binding, leaving the flap either open in AHA-, boric acid- and fluoride-inhibited urease, like in the native enzyme or closed in PPD-inhibited urease. Among the inhibitors, only PPD was found to be able to thoroughly protect the flap cysteines from the further reaction with disulfides, this apparently resulting from the closed conformation of the flap. Accordingly, in practical terms PPD may be regarded as the most suitable inhibitor for active-site protection experiments in inhibition studies of urease. 相似文献
1