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Spin‐Labeled Riboswitch Synthesized from a Protected TPA Phosphoramidite Building Block
Author(s) -
Kaiser Frank,
Endeward Burkhard,
Collauto Alberto,
Scheffer Ute,
Prisner Thomas F.,
Göbel Michael W.
Publication year - 2022
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202201822
Subject(s) - phosphoramidite , chemistry , site directed spin labeling , electron paramagnetic resonance , nitroxide mediated radical polymerization , photochemistry , combinatorial chemistry , nuclear magnetic resonance , polymerization , organic chemistry , biochemistry , polymer , oligonucleotide , physics , dna , radical polymerization
The nitroxide TPA (2,2,5,5‐tetramethyl‐pyrrolin‐1‐oxyl‐3‐acetylene) is an excellent spin label for EPR studies of RNA. Previous synthetic methods, however, are complicated and require special equipment. Herein, we describe a uridine derived phosphoramidite with a photocaged TPA unit attached. The light sensitive 2‐nitrobenzyloxymethyl group can be removed in high yield by short irradiation at 365 nm. Based on this approach, a doubly spin‐labeled 27mer neomycin sensing riboswitch was synthesized and studied by PELDOR. The overall thermal stability of the fold is not much reduced by TPA. In‐line probing nevertheless detected changes in local mobility.