首页> 外文期刊>International journal of environmental analytical chemistry >Characterization of urease derived from Citrullus lanatus (watermelon) seeds to estimate total Kjeldahl nitrogen in human urine
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Characterization of urease derived from Citrullus lanatus (watermelon) seeds to estimate total Kjeldahl nitrogen in human urine

机译:表征柑桔(西瓜)种子中的脲酶,以估计人尿中的凯氏总氮

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摘要

A urease extract prepared by decanting liquid from a suspension of finely ground Citrullus lanatus (watermelon) seeds was characterized and applied to dilute urine samples to demonstrate a low-cost field method to estimate total Kjeldahl nitrogen (TKN) concentrations in human urine. The extract exhibited a Michaelis-Menten constant, K-m, of 3.00 mM urea and a specific activity of up to 12.2 U/mg protein at an optimum pH of 8.1. A statistical F-test on 54 samples demonstrated that TKN can be estimated as the total ammonium-nitrogen recovered upon addition of urease in dilute fresh and stale urine samples. The total ammonium-nitrogen in urine samples determined after treatment with watermelon seed urease was consistent with that determined using traditional acid digestion techniques. The extract retained 85% of its initial capacity after three months of refrigeration. The effectiveness of this method to assay nitrogen in unbuffered urine samples will be useful in nitrogen analyses in nutrient recovery and urine or slurry storage contexts. Accordingly, this study is useful in understanding the kinetics of a plant-derived urease acting in dilute urine.
机译:通过从细磨的柑桔(西瓜)种子悬浮液中de析液体而制备的尿素酶提取物经过表征,并应用于稀尿样品中,以展示一种低成本的现场方法来估算人尿中凯氏总氮(TKN)的浓度。提取物表现出3.00 mM尿素的迈克尔斯-门腾常数K-m,在8.1的最佳pH下具有高达12.2 U / mg蛋白的比活。对54个样品的统计F检验表明,TKN可以估计为在稀的新鲜和陈旧尿液样品中添加尿素酶后回收的总铵氮。用西瓜籽尿素酶处理后测定的尿液样品中的总铵氮与使用传统酸消化技术测定的总氮一致。冷藏三个月后,提取物保留了其初始容量的85%。该方法在未缓冲尿液样品中测定氮的有效性将对营养物回收和尿液或泥浆存储环境中的氮分析有用。因此,该研究对于理解稀尿中作用于植物的脲酶的动力学是有用的。

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