Antonowicz I, Hesford F J, Green J R, Grogg P, Hadorn B
Clin Chim Acta. 1980 Feb 14;101(1):69-76. doi: 10.1016/0009-8981(80)90057-1.
The application of a new synthetic substrate to the direct determination of enteropeptidase is described. The substrate Gly-(L-Asp)4-L-Lys-2-naphthylamide contains the amino acid sequence of the activation peptides of trypsinogen linked via an amide bond to the fluorophore 2-naphthylamine. The sequence of amino acids is responsible for the specificity and substrate recognition of the enteropeptidase-catalyzed activation of trypsinogen. Interference in the assay by trypsin is prevented by the addition of soybean trypsin inhibitor to the substrate solution. The fluorimetric determination of the liberated 2-naphthylamine allows the direct observation of the reaction kinetics. For the hyrolysis of the synthetic substrate by purified enteropeptidase the pH optimum was 8.2 and the Km 0.17 mmol/l. The new substrate was used to determine the distribution of enteropeptidase along the rat small intestine and also to measure enteropeptidase activity in human intestinal biopsies.
本文描述了一种新型合成底物在直接测定肠肽酶中的应用。底物甘氨酸-（L-天冬氨酸）4-L-赖氨酸-2-萘酰胺包含通过酰胺键与荧光团2-萘胺相连的胰蛋白酶原激活肽的氨基酸序列。氨基酸序列决定了肠肽酶催化胰蛋白酶原激活的特异性和底物识别。通过向底物溶液中添加大豆胰蛋白酶抑制剂可防止胰蛋白酶对测定的干扰。对释放的2-萘胺进行荧光测定可直接观察反应动力学。对于纯化的肠肽酶对合成底物的水解，最适pH为8.2，Km为0.17 mmol/l。这种新型底物用于测定大鼠小肠中肠肽酶的分布，也用于测量人肠道活检组织中的肠肽酶活性。
