(A) Purified His6 protein was assayed for the ability to synthesize c-di-GMP. HPLC analysis for the detection of c-di-GMP and pGpG: (a): GTP, (b): Purified c-di-GMP, (c): With protein MtbDGC, separated on reversed phase HPLC. MALDI TOF analysis of the relevant HPLC fractions, in the positive ion detection mode, ions were detected at m/z of 542 (M+H)+ for GTP, 691 (M+H)+ and 713 (M+Na)+ for c-di-GMP, 709 (M+H)+ and 731 (M + Na)+ for pGpG. (B) Purified His6 protein was assayed for the ability to degrade c-di-GMP. HPLC analysis for the detection of pGpG. (c): Purified c-di-GMP (C): With Protein (MtbPDE),. MALDI TOF analysis of the relevant HPLC fractions, in the positive ion detection mode, ions were detected at m/z = 691 (M+H)+ and 713 (M+Na)+ for c-di-GMP, 709 (M+H)+ and 731 (M + Na)+ for pGpG.