High performance liquid chromatography (HPLC)
Nucleotides were extracted from purified Rv2623 by boiling. Samples were then loaded onto an analytical, anion-exchange HPLC column (AX300, Eprogen Inc. or Mono Q HR 5/5, GE Healthcare). Samples were eluted isocratically using NaH2PO4, pH 5.5 (AX300) or using a ammonium phosphate pH 7.0 (0.02–1.0 M) step gradient (Mono Q) (Text S1). Nucleotides were identified on the basis of retention time relative to nucleotide standards, and quantified by peak area.