The subject invention provides substrates useful for analyzing the metabolic activity in cells by improving the retention of a detectable reporter molecule only in intact cells where a particular enzyme is present. In particular, improved retention results from a two part process involving conjugation of haloalkyl-substituted derivatives of a reporter molecule with intracellular cysteine-containing peptides while unblocking the reporter molecule. The substrates have the form
XR-SPACER-REPORTER-BLOCK
wherein -BLOCK is a group selected to be removable by action of a specific analyte, to give REPORTER spectral properties different from those of the substrate,
-REPORTER- is a molecule that, when no longer bound to BLOCK by a BLOCK-REPORTER bond, has spectral properties different from those of the substrate,
-SPACER- is a covalent linkage, and
XR- is a haloalkyl moiety that can covalently react with an intracellular thiol (Z-S-H) to form a thioether conjugate (Z-S-R).
After the substrate enters the cells, the analyte removes BLOCK to make REPORTER detectable by the change in spectral properties, and the haloalkyl XR reacts with the intracellular thiol to form the thioether conjugate inside the cells, which is well-retained in the cells.
本发明提供了用于分析细胞代谢活性的底物,通过改善检测报告分子仅在存在特定酶的完整细胞中的保留能力。具体而言,改进的保留是由于一个两部分的过程,涉及将报告分子的卤代烷基衍
生物与细胞内含有半胱
氨酸的肽共轭,同时解除报告分子的阻断。底物具有以下形式XR-S
PACER-REPORTER-BLOCK,其中-BLOCK是一种可被特定分析物作用去除的基团,以给出与底物不同的REPORTER光谱特性,-REPORTER-是一种分子,当不再通过BLOCK-REPORTER键结合到BLOCK上时,具有与底物不同的光谱特性,-S
PACER-是一种共价连接,而XR-是一种卤代烷基,可以与细胞内的巯基(Z-S-H)共价反应,形成
硫醚共轭物(Z-S-R)。在底物进入细胞后,分析物去除BLOCK,通过光谱特性的变化使REPORTER可检测,而卤代烷基XR与细胞内的巯基反应,形成细胞内的
硫醚共轭物,这些共轭物在细胞内得到很好的保留。