Fig. 1
From: Sources of artifact in measurements of 6mA and 4mC abundance in eukaryotic genomic DNA
Purified nucleases and phosphatases contain methylated DNA. a UHPLC-ms/ms chromatography peaks of nucleoside standards corresponding to unmodified deoxycytidine (dC) and methylated deoxycytidines (3mC, 4mC or 5mC). b UHPLC-ms/ms chromatography peaks of nucleoside standards corresponding to unmodified deoxadenosine (dA) and N6-methylated deoxyadenosine (6mA). c Calculated molarity of 6mA (left panel) and adenine (right panel) in the three enzyme mixes: 1) Nuclease P1 mix (Nuclease P1, Phosphodiesterase 1, and alkaline phosphatase), 2) DNA degradase Plus, and 3) Nuclease S1 mix (Nuclease S1 and Fast alkaline phosphatase) reveals that the Nuclease P1 mix is more heavily contaminated than DNA degradase or Nuclease S1 mix. d Molarity of 4mC (left panel) and cytosine (right panel) in the three enzyme mixes shows that Nuclease P1 mix is more heavily contaminated than other digestion mixes. e Molarity of 3mC and 5mC in the three enzyme mixes shows that Nuclease P1 mix is more heavily contaminated than other digestion mixes. Each bar represents the mean +/− standard error of the mean for 3–10 independent mock reactions