Fig. 4
![Fig. 4](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12933-018-0684-1/MediaObjects/12933_2018_684_Fig4_HTML.gif)
Isomeric configuration phosphorothioate modification. Formation of diastereomers by phosphorothioate (PS) backbone modifications. a, b Chiral arrangements of Sp and Rp diastereomers. c, d Formation of 3′-phosphorothioate and 5′-phosphorothioate inter-nucleotide linkage from Sp and Rp diastereomers