Fluorescent labeling of tRNA dihydrouridine residues: Mechanism and distribution

Quantification and identification of Cy3-labeled RNase A oligonucleotides. (A) TLC analysis of digest of Cy3-labeled tRNA^Arg. Lane I, digest; lane II, digest plus added Cy3-hydrazide. (B) MALDI spectra—(i) Cy3-labeled tRNA^Arg digest, showing Cy3-D¹⁷ peak at m/z 937.4 (Na+ adduct at 959.4) and Cy3-GGAD^20a peak at m/z 1956.6, respectively; (ii) and (iii); parallel spectra for bands 1 and 2 (A), respectively. The peak at m/z 1978.7 corresponds to the Na+ adduct of Cy3-GGAD^20a. (C) TLC analysis of digest of Cy3-labeled tRNA^Phe. Lane I, Cy3-hydrazide; lane II, digest. (D) MALDI spectra—(i): Cy3-labeled tRNA^Phe digest, showing Cy3-AGD¹⁶ peak at m/z 1629.5 and Cy3-GGD²⁰ peak at m/z 1645.5, respectively; (ii) and (iii); parallel spectra for bands 1 and 2 (C), respectively.