人胰腺和唾液α-淀粉酶对α-4-硝基苯基麦芽庚糖苷底物的作用机制

Mechanism of action of human pancreatic and salivary alpha-amylase on alpha-4-nitrophenyl maltoheptaoside substrate.

作者信息

Hägele E O, Schaich E, Rauscher E, Lehmann P, Bürk H, Wahlefeld A W

出版信息

Clin Chem. 1982 Nov;28(11):2201-5.

PMID:6181912

Abstract

We evaluated the enzymic mechanism by which alpha-4-nitrophenyl maltoheptaoside serves as a substrate for serum amylase (EC 3.2.1.1). Because polymeric substrates possess many potential sites of cleavage, the expression of enzymic activity as the number of micromoles of substrate transformed under defined conditions by an enzyme must be changed to "one microequivalent of group transformed." Therefore, we measured the activity of the isoenzymes of alpha-amylase with regard to suitable oligosaccharide substrates, which allowed us to express the catalytic activity in IUB units (U). By "high-performance" liquid chromatography we investigated the mechanism of human pancreatic and salivary alpha-amylase action, both alone and in combination with alpha-glucosidase (EC 3.2.1.20). On the basis of these results, we can describe exactly the entire reaction sequence and determine the stoichiometric coefficient of 4-nitrophenol within 0.02 mol/L (SD) produced under the assay conditions.

摘要

我们评估了α-4-硝基苯基麦芽庚糖苷作为血清淀粉酶（EC 3.2.1.1）底物的酶促机制。由于聚合底物具有许多潜在的裂解位点，因此将酶活性表示为在特定条件下酶转化的底物微摩尔数，必须改为“转化的一个微当量基团”。因此，我们针对合适的寡糖底物测量了α-淀粉酶同工酶的活性，这使我们能够以国际生物化学与分子生物学联盟（IUB）单位（U）来表示催化活性。通过“高效”液相色谱法，我们研究了人胰腺和唾液α-淀粉酶单独作用以及与α-葡萄糖苷酶（EC 3.2.1.20）联合作用的机制。基于这些结果，我们能够准确描述整个反应序列，并确定在测定条件下产生的4-硝基苯酚在0.02 mol/L（标准差）范围内的化学计量系数。