FIGURE 3.

Conversion of [f⁵U]TSL into products upon incubation with TruB. (A) A portion of the C₁₈ HPLC traces of intact stem–loop before (broken line) and after (solid line) incubation with TruB showing quantitative conversion of [f⁵U]TSL into products. (B) A portion of the C₁₈ HPLC traces of the nucleosides resulting from digestion of [f⁵U]TSL before (broken line) and after (solid line) incubation with TruB; the void peak is labeled with an asterisk. (C) MALDI-TOF mass spectrum of intact [f⁵U]TSL before (broken line) and after (solid line) incubation with TruB; the shift of 18 m/z is that expected for hydration. (D) The structures of the likely products from f⁵U; the stereochemistry at C5 is assigned on the basis of the appearance of the depicted cis isomer (within the RNA stem–loop) in the cocrystal structure of TruB (Hoang and Ferre-D’Amare 1991).