A DNA sequencing system and method are described to detect the presence of radiant energy emitted from different excited reporter dye-labeled species (DNA fragments) following separation in time and/or space, and the identity of the species which emit radiant energy closely spaced in wavelength. Functions of the emitted energy are obtained which vary over the wavelengths of the closely spaced spectra in different senses and the functions ratioed, whereby the ratio is indicative of the identity of the DNA fragments.
The emitting portion of the reporter-labeled DNA fragment is preferably one of a family of fluorescent dyes based on 9-carboxyethyl-6-hydroxy-3-oxo-3H-xanthene. These xanthene dyes are covalently attached to the DNA fragments through the carboxylic acid functionality, preferably via an amide linkage. The dyes may be protected by including an alkoxy group at the 9-position. A spacer may be inserted between the dye and the amine. The fluorescent dye preferably is attached to the DNA chain terminators and provides many advantages. Thus only DNA sequencing fragments resulting from bona fide termination events will carry a reporter. The DNA sequencing may also be labeled using the xanthene dyes which have general utility as fluorescent labels. Also acyclonucleoside triphosphates are described as being useful as chain terminators in DNA sequencing using a modification of the Sanger method.
描述了一种 DNA 测序系统和方法,用于检测在时间和/或空间上分离后不同激发的报告
染料标记物种(DNA 片段)所发射的辐射能量的存在,以及发射辐射能量的波长间隔很近的物种的特性。可以获得发射能量的函数,这些函数在不同波长的紧密间隔光谱上变化,并将这些函数进行比对,比对结果显示 DNA 片段的特征。
报告标记 DNA 片段的发射部分最好是基于 9-羧乙基-6-羟基-3-氧代-3H-
氧杂蒽的荧光
染料家族中的一种。这些
氧杂蒽染料通过
羧酸官能团共价连接到 DNA 片段上,最好是通过酰胺连接。
染料可以通过在 9 位加入一个烷氧基来保护。
染料和胺之间可以插入一个间隔物。荧光
染料最好连接到 DNA 链终止器上,这样做有许多优点。因此,只有真正终止事件产生的 DNA 测序片段才会带有报告物。DNA 测序也可以使用呫吨
染料进行标记,这种
染料一般用作荧光标记。此外,无环核苷
三磷酸酯也可作为DNA测序中的链终止器,使用桑格测序法的一种改良方法。