PHOSPHORUS-31 SOLID-STATE NMR CHARACTERIZATION OF OLIGONUCLEOTIDES COVALENTLY BOUND TO A SOLID SUPPORT

P-31 cross polarization (CP) magic angle spinning (MAS) nuclear magnet ic resonance (NMR) spectra were acquired for various linear and branch ed di- and tri-nucleotides attached to a controlled pore glass (CPG) s olid support, The technique readily distinguishes the oxidation state of the phosphorus atom (phosphate versus phosphite), the presence or a bsence of a protecting group attached directly to phosphorus (cyanoeth yl), and other large changes in the phosphorus chemistry (phosphate ve rsus phosphorothioate), However, differences in configurational detail s remote from the phosphorus atom, such as the attachment position of the ribose sugar (2'5' versus 3'5'), or the particulars of the nucleot ide bases (adenine versus uridine versus thymine), could not be resolv ed. When different stages of the oligonucleotide synthetic cycle were examined, P-31 CPMAS NMR revealed that the cyanoethyl protecting group is removed during the course of chain assembly.