Enzymatic release of phosphate from model substrates and P compounds in soil solution from a peaty podzol
Enzymatic release of phosphate from model substrates and P compounds in soil solution from a peaty podzol
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泥炭灰化土壤溶液中模型底物和磷化合物的酶促释放
DOI：
10.1007/s003740050229
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发表时间：
1997
影响因子：
6.5
通讯作者：
S. Smith
中科院分区：
文献类型：
--
作者：
C. Shand;S. Smith
在pH 5.0的条件下，酸性磷酸酶或植酸酶在<6 h内定量释放模型酯和多磷酸（葡萄糖磷酸、肌醇六磷酸、焦磷酸、核糖核酸、三聚磷酸和三偏磷酸）溶液中的磷酸盐。在比色法测定释放的钼酸盐活性磷时，加入二甲基亚砜消除了酶中蛋白质与磷钼蓝之间形成的不溶性离子缔合物的干扰。过滤后（0.45 μm）泥炭土中总溶解磷（TDP）含量为590 μg dm-3，其中钼酸盐活性磷（MRP）占13%，溶解有机磷（DOP）占26%，溶解凝聚磷（DCP）占61%。在土壤溶液中加入酸性磷酸酶水解模型化合物时，MRP在10 h左右增加到TDP的54%，然后保持不变。从质量平衡来看，至少有25%的DCP被水解。土壤溶液在35°C下无酶孵育，MRP提高到TDP的44%，反映了天然酶的活性。土壤溶液中TDP浓度较高（1.27 mg dm-3）。MRP、DOP和DCP的分布相似，但酸性磷酸酶水解P的比例更大，MRP增加到TDP的64%，DCP至少有40%被水解。植酸酶与酸性磷酸酶的水解结果相似。部分DOP或DCP免受水解的保护可能是由于胶体内的闭塞或与模型底物不同的P化合物的存在。
Abstract Phosphate in solutions of model esters and polyphosphates (glucose phosphate, inositol hexaphosphate, pyrophosphate, ribonucleic acid, tripolyphosphate and trimetaphosphate) was quantitatively released in <6 h by acid phosphatase or phytase at pH 5.0. Interference from insoluble, ion association complexes formed between protein in the enzymes and the phosphomolybdenum blue during the colorimetric determination of the molybdate reactive phosphorus released was removed by adding dimethyl sulphoxide. Filtered (0.45 μm) soil solution from a peaty soil contained 590 μg dm–3 total dissolved phosphorus (TDP), of which 13% was molybdate reactive phosphorus (MRP), 26% dissolved organic phosphorus (DOP) and 61% dissolved condensed phosphorus (DCP). When acid phosphatase was added to the soil solution under the conditions used to hydrolyse the model compounds, MRP increased to 54% of the TDP in about 10 h and then remained constant. From a mass balance, at least 25% of the DCP was hydrolysed. Incubation of the soil solution at 35°C without enzyme increased MRP to 44% of the TDP, reflecting native enzyme activity. Soil solution containing a higher concentration of TDP (1.27 mg dm–3) was also obtained. The distribution of MRP, DOP and DCP fractions was similar but acid phosphatase hydrolysed a greater proportion of the P and MRP increased to 64% of the TDP and at least 40% of the DCP was hydrolysed. The results of hydrolysis with phytase were similar to those with acid phosphatase. The protection of part of the DOP or DCP fraction from hydrolysis was likely caused by occlusion within colloids or the existence of P compounds unlike those of the model substrates.