Synthesis and Characterization of Oligoribonucleotides

Oligoribonucleotides for UV-melting experiments, DNA primers for PCR reactions, and 5′-FAM labeled DNA primers for reverse transcription in SHAPE experiments were synthesized on a BioAutomation MerMade12 DNA/RNA synthesizer using β-cyanoethyl phosphoramidite chemistry as described previously [52 (link)], and commercially available phosphoramidites (ChemGenes (Wilmington, MA, USA); GenePharma (Shanghai, China)). The details of deprotection and purification of oligoribonucleotides were also described previously [52 (link)]. Thin-layer chromatography (TLC) purification of the oligonucleotides was carried out on Merck 60 F254 TLC plates with the mixture of 1-propanol/aqueous ammonia/water = 55:35:10 (v/v/v). After synthesis and purification, oligonucleotides were verified using mass spectroscopy (MALDI-ToF).