Figure 2.

Common background signals. A) Examplary UV‐active reactants 1 and 3. B) Standard background observed from the absorption of the 96‐well plate filled with water or aqueous NaOH. Signals for 1 and 3 represent typical signal intensities observed for reactions with 2 mM nucleoside substrate and a dilution factor of 15 during sampling. C) Baseline shift observed in approximately 1–2 % of measurements. D) Background observed in reactions with significant protein content. Purified Escherichia coli thymidine phosphorylase was used to recreate typical protein backgrounds by 15‐fold dilution in 100 mM NaOH. Note that some proteins can cause significantly more or less background. E) Representative background observed with some organic solvents. DMF was diluted tenfold in 100 mM NaOH to record the background signals.