土壤蔗糖酶(Solid-Sucrase, S-SC）试剂盒说明书

                                       分光光度法50管/24样

注    意：正式测定务必取2-3个预期差异较大的样本做预测定

测定意义：

S-SC能够水解蔗糖变成相应的单糖而被机体吸收，其酶促作用产物与土壤中有机质、氮、磷含量，微生物数量及土壤呼吸强度密切关，是评价土壤肥力的重要指标。

测定原理：

S-SC催化蔗糖降解产生还原糖，进一步与3，5－二硝基水杨酸反应，生成棕红色氨基化合物，在510nm有特征光吸收，在一定范围内510nm光吸收增加速率与S-SC活性成正比。

自备用品：

可见分光光度计、台式离心机、水浴锅、可调式移液器、1mL玻璃比色皿、甲苯（不允许快递）和蒸馏水。

试剂组成和配制：                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

试剂一：甲苯5mL×1瓶，4℃保存；（自备）

试剂二：液体15mL×1瓶，4℃保存；

试剂三：粉剂×1瓶，4℃保存；临用每瓶加入40mL蒸馏水充分溶解备用；用不完的试剂4℃保存；

试剂四：液体30mL×1瓶，4℃保存。

样品处理：

新鲜土样自然风干或37度烘箱风干，过30~50目筛。

测定步骤和加样表：

振荡混匀，使土样全部湿润，37℃水浴15min

充分混匀，放入37℃水浴培养24小时，10000 g，4℃，离心5min，取上清液

充分混匀，95℃水浴5min（盖紧，以防止水分散失），流水冷却后充分混匀，蒸馏水稀释10倍后（可以吸取100μL，加入900μL蒸馏水稀释；如果吸光度大于4，可以适当加大稀释倍数），510nm处蒸馏水调零，读吸光值A。计算ΔA=A测定管-A对照管。每个测定管需设一个对照管。

S-SC活性计算：

标准条件下测定的回归方程为y = 4.9x -0.062；x为标准品浓度（mg/mL），y为吸光值。

单位的定义：每天每g土样中产生1mg 还原糖定义为一个S-SC活力单位。

S-SC活力(mg/d /g 土样)=( ΔA+0.062) ÷4.9×10×V反总÷W÷T =20.7×(ΔA+0.062)

10：稀释倍数；T：反应时间，1d； V反总：反应体系总体积：1.015mL；W：样本质量，0.1g。