Dihydro-rhodamine

The idea to analyze the catalysis by a single enzyme molecule was an obvious step. This was first demonstrated by Peter Lu and Sunney Xie [38]. They were able to show intensity fluctuation of the flavin cofactor of cholesterol oxidase using confocal single molecule detection. Our idea of single enzyme catalysis was to follow the turnover of a substrate into the product by catalysis of a single enz une molecule. We chose horse radish peroxidase and a non-fluorescence substrate dihydro-rhodamine which is turned over in the fluorescent product... 

Fig. 4.15. Setup for measuring the turnover of dihydro-rhodamin by horse radish peroxidase bound to a coverslip by biotin-streptavidin interaction...

Fig. 4.23. NMF for surface bound horse radish peroxidase in the presence of dihydro-rhodamin (100 nM) as substrate (a). Control without enzyme (b)...

We investigated the kinetics of the catalytic cycle of single horseradish peroxidase enzymes when hydrogen peroxide (H2O2) as an electron donor is processed for oxidizing (dihydro)Rhodamine 123, thereby generating Rhodamine 123 (Rhl23) (30 and references therein). 

Qin, Y. Lu, M. Gong, X. Dihydrorhodamine 123 is superior to 2,7-dichlorodihydrofluorescein diacetate and dihydro-rhodamine 6G in detecting intracellular hydrogen peroxide in tumor cells. Gell Biol. Int. 2008, 32, 224-228. 

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