REDUCING VALUE METHODS FOR MALTODEXTRINS .1. CHAIN-LENGTH DEPENDENCE OF ALKALINE 3,5-DINITROSALICYLATE AND CHAIN-LENGTH INDEPENDENCE OF ALKALINE COPPER
REDUCING VALUE METHODS FOR MALTODEXTRINS .1. CHAIN-LENGTH DEPENDENCE OF ALKALINE 3,5-DINITROSALICYLATE AND CHAIN-LENGTH INDEPENDENCE OF ALKALINE COPPER
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DOI：
10.1016/0003-2697(72)90213-8
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发表时间：
1972-01-01
影响因子：
2.9
通讯作者：
WHELAN, WJ
中科院分区：
文献类型：
--
作者：
ROBYT, JF;WHELAN, WJ
使用碱性 3,5-二硝基水杨酸盐和碱性铜试剂获得麦芽糖糊精（麦芽糖-麦芽七糖）的摩尔还原值。结果发现，等摩尔量的麦芽糖糊精对碱性3,5-二硝基水杨酸盐的吸光度值随着糊精中葡萄糖单元的数量而增加。然而，钙离子 (40 mM) 抑制吸光度值的增加，但并不能完全消除过度氧化。对于等摩尔量的麦芽糖糊精，碱性铜试剂给出恒定的吸光度值。因此，碱性铜试剂与半缩醛、还原基团的数量呈现化学计量关系，而碱性3,5-二硝基水杨酸盐则呈现非化学计量关系。这些结果对糖酶活性的测量具有重要影响。通过碱性 3,5-二硝基水杨酸盐测定 α-淀粉酶与酶浓度呈曲线关系，而通过碱性铜测定则呈现线性关系。使用二硝基水杨酸盐会对 α-淀粉酶活性做出错误的高估计，并且很明显，钙对二硝基水杨酸盐降低值的影响误导了一些工作人员，认为该离子影响 α-淀粉酶作用模式。
Molar reducing values for maltodextrins (maltose-maltoheptaose) were obtained using alkaline 3,5-dinitrosalicylate and alkaline copper reagents. It was found that equimolar quantities of the maltodextrins gave absorbance values with alkaline 3,5-dintrosalicylate that increased with the number of glucose units in the dextrin. Calcium ion (40 mM), however, repressed the increase in the absorbance values but did not completely eliminate overoxidation. The alkaline copper reagent gave a constant absorbance value for equimolar quantities of the maltodextrins. Thus, alkaline copper reagent gives a stoichiometric relationship with the number of hemiacetal, reducing groups, and alkaline 3,5-dinitrosalicylate gives a nonstoichiometric relationship. These results have an important consequence on the measurement of carbohydrase activity. The assay of α-amylase by alkaline 3,5-dinitrosalicylate gives a curvilinear relationship with enzyme concentration, whereas the assay by alkaline copper gives a linear relationship. The use of dinitrosalicylate will give erroneously high estimates of α-amylase activity, and it is clear that the effect of calcium on dinitrosalicylate reducing values has misled some workers into concluding that this ion affects α-amylase action patterns.