Fluorescent labeling of RNA and DNA on the Hoogsteen edge using sulfinate chemistry

(A) LC/MS chromatograms of the four DAAS-labeled nucleosides (indicated by arrows), produced from a digested DAAS-labeled O.i. sample. A blank is included. Structures are included on the right, color coded to their respective chromatograms. The extra peak for DAAS-labeled guanosine at 18.81 min results from an unrelated mass from the blank. The peak at 19.35 min corresponds to the actual DAAS-labeled guanosine species. (B) LC/MS chromatograms of the four canonical nucleosides (indicated by arrows), produced from a digested DAAS-labeled O.i. sample. A blank is included. Structures are included on the right, color coded to their respective chromatograms. The extra uridine peak at 3.52 min results from cytidine overlap (likely caused by natural ¹³C incorporation) due to their difference of only 1 AMU.