Formamide significantly enhances the efficiency of chemical adenylation of RNA sequencing ligation adaptors

Formamide increases the yield of chemical adenylation. (A) Schematic of the adenylation reaction. (B) Adenylation of a 5′ phosphorylated DNA oligonucleotide (ODN1) with the reaction taking place either in water or in 95% formamide. (C) Ligation of a 5′ p-DNA oligonucleotide or a 5′ App-DNA oligonucleotide (ODN1) that was adenylated in formamide to an RNA oligonucleotide (ORN1) using a mutant RNA ligase that requires a preadenylated ligation donor.