@article{
author = "Prodanović, Radivoje and Ostafe, Raluca and Blanusa, Milan and Schwaneberg, Ulrich",
year = "2012",
abstract = "A Vanadium bromoPeroxidase-coupled fluorescent assay (ViPer) for ultrahigh-throughput screening of glucose oxidase (GOx) gene libraries employing double emulsions and flow cytometry was developed. The assay is based on detection of the product of a GOx reaction, hydrogen peroxide, that is first converted to a hypobromide by vanadium bromoperoxidase in the presence of sodium bromide. The hypobromide is afterwards detected in a reaction with a fluorogenic probe, 3-carboxy-7-(4'-aminophenoxy)-coumarine, where fluorescent 3-carboxy-coumarine is released. The ViPer screening system is three times more sensitive than a horseradish peroxidase coupled detection system and more resistant to bleaching of fluorescence in excess of peroxide. Using the ViPer screening system a high epPCR gene library containing 100,000 different GOx variants was screened for active clones in less than 1 h by flow cytometry. A library containing 0.15 % of yeast cells expressing active enzyme variants and with an average GOx activity in the liquid culture of 0.47 U/mL, after one round of sorting, had 28.12 % of the yeast cells expressing the active GOx (an enrichment factor of 200) and 26.8 U/mL of the GOx activity in the liquid culture (an enrichment factor of 57). The developed screening system could be adapted and used in a directed evolution of GOx and other hydrogen peroxide-producing enzymes (oxidases) and glycosidases if coupled with a carbohydrate oxidase.",
publisher = "Springer Heidelberg, Heidelberg",
journal = "Analytical and Bioanalytical Chemistry",
title = "Vanadium bromoperoxidase-coupled fluorescent assay for flow cytometry sorting of glucose oxidase gene libraries in double emulsions",
volume = "404",
number = "5",
pages = "1439-1447",
doi = "10.1007/s00216-012-6234-x"
}