| abstract |
Compounds and method for assaying enzymes by adding to a medium containing an enzyme a stable free radical compound having a stable free radical functionality, bonded directly or indirectly to an enzyme labile functionality, which when subjected to an enzyme catalyzed reaction changes the environment of the free radical functionality. By following the change in the electron spin resonance (ESR) spectrum as affected by the change in environment, the type of enzyme and activity of enzyme may be determined. The compounds which find use in this invention are normally stable nitroxide radicals. Particularly, nitronyl nitroxides, with the nitrogens in an imidazoline ring are employed, having a methylene group joining the 2 position of the imidazoline ring with an asymmetric carbon atom. One of the groups bonded to the asymmetric carbon atoms has an enzyme labile functionality. Other compounds include two cyclic nitroxide containing rings joined by a chain having an enzyme labile functionality. |