Figure 2.

(a) Spin labeling reaction based on the “click”-reaction. THPTA = Tris(3-hydroxypropyltriazolyl-methyl)amine; DMSO = dimethylsulfoxide. (b) Sequence of the single-stranded RNA and the annealed duplex. The letter U marked in bold corresponds to the labeling positions. In the following, the RNA single strand labeled with 1^• is called A while the one labeled with 2^• is called B. The spin labeled single-stranded RNAs A and B were annealed to obtain duplexes A₂ and B₂, respectively.