Conjugates of 2,3-dihydroxynaphthalene and its derivatives with enzyme cleavable groups are chromogenic substrates that form colored compounds when complexed with metal ions, e.g. iron ions, on cleavage by enzymes, and are useful in microbial detection and identification. The cleavage products form purple or red-brown colored complexes, that can easily be observed by the naked eye. Microbes can be grown in the presence of the substrates and the metal salts that provide the metal ion for complexing with the 2,3-dihydroxynaphthalene product. Substituents in the naphthalene ring may affect the solubility of the substrates and also the diffusibility and color of the metal complexes. Some of the substrates yield soluble complexes on cleavage and are of particular value in liquid growth media. Other substrates produce less soluble complexes that are more suitable for use in solid agar media.
Some substrates are new compounds, such as those having the general formula II
wherein one of the following applies
i) m=0, R4═R5=Z1═H, Y1 is selected from the group consisting of D-glucuronyl and D-ribofuranosyl;
ii) m=2, each R6 is Br, R4═R5═H or Br, Z1═H, Y1 is glycosyl or phosphate;
iii) m=1, R6 is —SO3X, X is H or M+ wherein M+ is an alkali metal cation or a non-metal cation, Y1 is glycosyl and R4═R5=Z1═H;
iv) m=0, R4═NO2, R5═Z1═H, Y1=glycosyl.
Methods of synthesizing the substrates are described.
2,3-二羟基萘及其衍
生物与酶可裂解基团的共轭物是一种发色底物,当与
金属离子(如
铁离子)络合时,在酶的裂解作用下形成有色化合物,可用于微
生物检测和鉴定。裂解产物形成紫色或红棕色的复合物,很容易用肉眼观察到。微
生物可在底物和
金属盐的存在下生长,
金属盐可提供与
2,3-二羟基萘产物络合的
金属离子。
萘环上的取代基可能会影响底物的溶解度以及
金属络合物的扩散性和颜色。一些底物在裂解时会产生可溶性络合物,在液体生长介质中具有特殊价值。其他底物产生的络合物溶解度较低,更适合在固体
琼脂培养基中使用。
有些底物是新化合物,如通式 II
其中下列情况之一适用
i) m=0,R4═R5=Z1═H,Y1选自由
D-葡萄糖醛酸基和D-
呋喃核糖基组成的组;
ii) m=2,每个 R6 是 Br,R4═R5═H 或 Br,Z1═H,Y1 是糖基或
磷酸;
iii) m=1,R6 是-SO3X,X 是 H 或 M+,其中 M+ 是碱
金属阳离子或非
金属阳离子,Y1 是糖基,R4═R5=Z1═H;
iv) m=0,R4═
NO2,R5═Z1═H,Y1=糖基。
说明了底物的合成方法。