Four N-acetyl-β-D-glucosaminides, 4-amino-2, 6-dibromophenyl (1a), 4-amino-2, 6-dichlorophenyl (1b), 4-amino-2-chlorophenyl (1c) and 4-aminophenyl N-acetyl-β-D-glucosaminides (1d) were synthesized. Substrates 1a-c were hydrolyzed by N-acetyl-β-D-glucosaminidase and the released aglycones reacted with N-ethyl-N-(3-methylphenyl)-N'-succinylethylenediamine to produce indoaniline dyes in the presence of bilirubin oxidase under weakly acidic rate-assay conditions (pH 5.0). The Km values for 1a-c were 1.97, 1.65 and 1.39 mM, respectively. Among these compounds, 1b is considered to be the substrate with most potential for the rate-assay of N-acetyl-β-D-glucosaminidase, since it showed the largest Vmax value and the strongest color generation from colorless to green (λmax 302→718 nm)following enzyme hydrolysis and the coupling reaction. Furthermore, 1b was moderately soluble and stable in aqueous solution and exhibited about a 5.9-fold higher sensitivity to the enzyme than 2-chloro-4-nitrophenyl N-acetyl-β-D-glucosaminide.
合成了四种 N-乙酰基-β-D-
氨基葡萄糖苷,即 4-
氨基-2,6-二
溴苯基(1a)、4-
氨基-2,6-二
氯苯基(1b)、4-
氨基-2-
氯苯基(1c)和 4-
氨基苯基 N-乙酰基-β-D-
氨基葡萄糖苷(1d)。底物 1a-c 被 N-乙酰基-β-D-
葡糖苷酶
水解,释放出的苷元与 N-乙基-N-(3-甲基苯基)-N'-丁二酰
乙二胺反应,在
胆红素氧化酶存在下,在弱酸性速率测定条件(pH 5.0)下生成
吲哚苯胺染料。1a-c 的 Km 值分别为 1.97、1.65 和 1.39 mM。在这些化合物中,1b 被认为是最有潜力用于 N-乙酰基-β-
D-葡萄糖苷酶速率测定的底物,因为它在酶
水解和偶联反应后显示出最大的 Vmax 值和最强的从无色到绿色的颜色生成(λmax 302→718 nm)。此外,1b 在
水溶液中具有中等溶解度和稳定性,对酶的敏感性比 2-
氯-4-
硝基苯基 N-乙酰基-β-D-
氨基葡萄糖苷高约 5.9 倍。