Henkel E, Morich S, Henkel R
J Clin Chem Clin Biochem. 1984 Jul;22(7):489-95. doi: 10.1515/cclm.1984.22.7.489.
Tests for the determination of alpha-amylase activity based on oligosaccharides or their 4-nitrophenyl derivatives as substrates suffer from some disadvantages. Using a more acid indicator molecule and connecting this group in the beta-form to maltoheptaose leads to a new substrate, 2-chloro-4-nitrophenyl-beta-D-maltoheptaoside, for the determination of alpha-amylase activity. Due to its pK value, only half of the 4-nitrophenol formed from 4-nitrophenyl-alpha-D-maltoheptaoside is spectrophotometrically detectable, whereas the total product from the new substrate is responsible for a measurable absorbance. In addition the molar lineic absorbance of the product is 1.8 times higher. Thus the new test is more sensitive than those employing 4-nitrophenyl derivatives. Both P-type and S-type alpha-amylase isoenzymes have the same affinity for the new substrate; this is not the case for all the other substrates, i.e. oligosaccharides and their 4-nitrophenyl derivatives, used in alpha-amylase tests. The sample volume may be reduced, thereby removing interference by substances like bilirubin, glucose and haemoglobin. The test is insensitive to changes in temperature and pH and can be adapted to all mechanized analytical instruments.
基于寡糖或其4-硝基苯基衍生物作为底物来测定α-淀粉酶活性的测试存在一些缺点。使用一种酸性更强的指示剂分子，并将该基团以β-型连接到麦芽七糖上，可得到一种用于测定α-淀粉酶活性的新底物，即2-氯-4-硝基苯基-β-D-麦芽七糖苷。由于其pK值，由4-硝基苯基-α-D-麦芽七糖苷形成的4-硝基苯酚中只有一半可通过分光光度法检测到，而新底物产生的总产物会导致可测量的吸光度。此外，产物的摩尔线性吸光度高出1.8倍。因此，新测试比使用4-硝基苯基衍生物的测试更灵敏。P型和S型α-淀粉酶同工酶对新底物具有相同的亲和力；而在α-淀粉酶测试中使用的所有其他底物，即寡糖及其4-硝基苯基衍生物，情况并非如此。样品体积可以减少，从而消除胆红素、葡萄糖和血红蛋白等物质的干扰。该测试对温度和pH的变化不敏感，并且可以适用于所有机械化分析仪器。
