were purchased from New England Biolabs (Ipswich, MA). Nuclease P1
from Penicillium citrinum was purchased
from Sigma-Aldrich (St. Louis, MO). All oligonucleotide primers were
obtained from Integrated DNA Technologies (Coralville, IA) and used
as received. Talon metal affinity resin was purchased from Clontech
(Mountain View, CA). PD-10 prepoured gel-filtration columns were purchased
from GE Biosciences (Piscataway, NJ). S-Adenosylmethionine
and S-adenosyl-[methyl-13C]methionine were synthesized enzymatically and purified as described
previously.27 (link) [2-2H]Adenosine
triphosphate (97% enrichment) was purchased from Cambridge Isotopes
(Andover, MA). The 155-mer and [2-2H]A-155-mer RNA substrates
(encompassing positions 2454–2608 of E. coli 23S rRNA) were prepared using runoff transcription as previously
described.25 (link)Ec flavodoxin
(Fld) and flavodoxin reductase (Flx) were purified as previously described.28 (link)