Synthesis and hybridizing properties of P-stereodefined chimeric [PS]-{DNA:RNA} and [PS]-{DNA:(2'-OMe)-RNA} oligomers.

Oxathiaphospholane derivatives of 2'-OMe-ribonucleosides and 2'--TBDMS-ribonucleosides (N-OTP and N-OTP, respectively; nucleobase protected) were synthesized and separated into pure P-diastereomers. X-ray analysis showed the absolute configuration of the phosphorus atom in the -eluting diastereomer of A-OTP. The - and -eluting P-diastereomers of N-OTP and N-OTP were used in the solid-phase synthesis of phosphorothioate dinucleotides (NT and NT, respectively), which were subsequently hydrolyzed with -selective phosphodiesterase svPDE and -selective nuclease P1 to determine the absolute configuration of the phosphorus atoms.

-Stereodefined phosphorothioate analogs of glycol nucleic acids-synthesis and structural properties.

Enantiomerically pure, protected acyclic nucleosides of the GNA type (glycol nucleic acids) (N'), obtained from ()-(+)- and ()-(-)-glycidols and the four canonical DNA nucleobases (Ade, Cyt, Gua and Thy), were transformed into 3'--DMT-protected 2-thio-4,4-pentamethylene-1,3,2-oxathiaphospholane derivatives (OTP-N') containing a second stereogenic center at the phosphorus atom. These monomers were chromatographically separated into -diastereoisomers, which were further used for the synthesis of -stereodefined "dinucleoside" phosphorothioates NT (N = A, C, G, T). The absolute configuration at the phosphorus atom for all eight NT was established enzymatically and verified chemically, and correlated with chromatographic mobility of the OTP-N' monomers on silica gel.

Guanosine in a single stranded region of anticodon stem-loop tRNA models is prone to oxidatively generated damage resulting in dehydroguanidinohydantoin and spiroiminodihydantoin lesions.

Oxidation of RNA hairpin models corresponding to anticodon stem-loop (ASL) of transfer RNA led to RNA damage consisting solely of a unique loop guanine oxidation. Manganese porphyrin/oxone treatment of RNA resulted in dehydroguanidinohydantoin (DGh; major) and/or spiroiminodihydantoin (Sp) lesions. Ribose damage was not observed.

LNA units present in the (2'-OMe)-RNA strand stabilize parallel duplexes (2'-OMe)-RNA/[All-R(P)-PS]-DNA and parallel triplexes (2'-OMe)-RNA/[All-R(P)-PS]-DNA/RNA. An improved tool for the inhibition of reverse transcription.

Homopurine phosphorothioate analogs of DNA, possessing all phosphorus atoms of RP configuration ([All-RP-PS]-DNA), when interact with appropriate complementary RNA or (2'-OMe)-RNA templates, form parallel triplexes or parallel duplexes of very high thermodynamic stability. The present results show that T-LNA or 5-Me-C-LNA units introduced into the parallel Hoogsteen-paired (2'-OMe)-RNA strands (up to four units in the oligomers of 9 or 12 nt in length) stabilize these parallel complexes. At neutral pH, dodecameric parallel duplexes have Tm values of 62-68 °C, which are by 4-10 °C higher than Tm for the reference duplex (with no LNA units present), while for the corresponding triplexes, Tm values exceeded 85 °C.