To assay PyNP-04 for the glycosylation of the Senucleobase 2, reactions consisting of 1 mM 2, 10 mM b' and 70 µg mL -1 enzyme in 50 mM glycine/NaOH buffer pH 9 were monitored. For analysis, samples of 60 µL were withdrawn, quenched in an equal volume of MeOH and diluted with 400 µL 100 mM glycine/NaOH buffer pH 10. The experimental spectra were fitted with corresponding reference spectra of 2 and 2b obtained under the same conditions.