Atividade de ureases em solos e avaliação de potenciais inibidores / Ureases activity in soil and potencial inhibitors evaluation

AUTOR(ES)

Ingrid Kely da Silva Santana

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

27/07/2011

RESUMO

The urease is an enzyme that catalyzes the hydrolysis of urea to carbon dioxide and ammonia. The inhibitors are used to minimize the volatilization of NH3 from hydrolysis of urea. The present study proposes to evaluate the activity of urease in crop, tillage and conventional system from pasture and eucalyptus and evaluate the compounds potential of imine and pyrimidinone groups in inhibitions of activity of urease in soil. Two experiments were conducted. On the first one the incubated was conducted in 30 and 4 oC. The treatments match of a factorial [(4 x 10) + 4], were four soils (pasture, SPC, SPD and eucalyptus), ten times of incubation (2, 4, 6, 12, 24, 36, 48, 72, 120 and 168 hours) further the control for each soil to the assay of 30 oC. In the assay with the temperature of 4o C were eight times of incubation until 72 hours, therefore factorial was [(4 x 8) + 4]. The delimitation was completely randomized with five repetitions. On the second essay the treatments match to a factorial ([(11 x 4) + 1] x 5) with 11 compounds (5 imine, 5 pyrimidinone and one PMA), four doses (0,25, 0,50, 0,75 e 1,0 μmol); further the treatment with inhibitor in five times of incubation 30 C (6, 12, 24, 48 e 72 h). The delimitation was divided in blocks at random with five repetitions. The urease activity in soil was evaluated determining the remaining of urea in different time of incubation. The urea was extracted through mixed solution of KCl 2 mol L-1 and 5 mg L-1 of phenylmercury acetate (PMA). The urea in the extract was quantified by spectrophotometer method (527 nm) using diacetyl monoxime (DAM) and thiosemicarbazide (TSC) in acid. The soils presented different potential of urea hydrolysis with temperature effect of incubation. The pasture soil presented higher activity ureolitic, followed by SPC, SPD and eucalyptus soil. The conformations evaluated of imine and pyrimidinone werent effective in the activity inhibition of ureases. Although no significance, the conformations of pyrimidinone analized were more effective in the activity urease inhibition. The pyrimidinone 10, with the application of 1,0 μmol, show the higher activity resulting in the time of 25 hours of incubation to hydrolise 90 % of ureia added to the soil, Other conformations of imine and pyrimidinone should be synthesized and evaluated their inhibitor potential.

ASSUNTO(S)

kinetics volatilization ureia amônia cinética volatização ciencia do solo urea ammonia

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