Cacodylic acid

Neomycin-B, paromomycin, ribostamycin, tobramycin, kanamycin-A, kanamycin-B, sisomicin, geneticin, netilmicin, and amikacin (Figs. 1A, 3B) were obtained as their sulfate salts from Sigma-Aldrich. All RNA oligonucleotides were from Integrated DNA Technologies Inc., and were maintained at −20°C in deionized distilled water (ddH₂O) until use. Sodium cacodylate was from Sigma-Aldrich and cacodylic acid was from Amresco. All other chemicals were from Fisher Scientific. Buffers were as follows: A (13.5 mM NaCl, 150 mM KCl, 20 mM HEPES, 0.22 mM Na₂HPO₄, 0.44 mM KH₂PO₄, 120 μM MgCl₂, 120 nM CaCl₂, 100 μM MgSO₄ at pH 7.3), N (10 mM Na₂HPO₄ at pH 7.3), and F (5 mM MgCl₂, 200 mM NH₄CI, 80 mM KCl, 80 mM Na-cacodylate at pH 7.4). All buffers were prepared with deionized distilled water and their pH's were measured at 25°C. Sequences of the RNA aptamers used in this study are shown in Supplemental Table S1. The buffer components used to determine the effect of [I] on aminoglycoside binding are listed in Supplemental Table S2.