A nucleotide dimer synthesis without protecting groups using montmorillonite as catalyst.

A synthesis has been developed providing nucleotide dimers comprising natural or unnatural nucleoside residues. A ribonucleoside 5'-phosphorimidazolide is added to a nucleoside adsorbed on montmorillonite at neutral pH with the absence of protecting groups. Approximately 30% of the imidazolide is converted into each 2'-5' dimer and 3'-5' dimer with the rest hydrolyzed to the 5'-monophosphate.

MALDI analysis of oligonucleotides directly from montmorillonite.

Oligonucleotides synthesized on a montmorillonite catalyst were analyzed directly. By mixing the catalyst with a matrix (2,4,6-trihydroxyacetophenone or 6-aza-2-thiothymine) and dibasic ammonium citrate, higher molecular weight products were detected compared with "classical" methods such as gel electrophoresis and HPLC with UV as a detector. The oligomers (30-mers and higher) were detected by mass spectrometry even though their concentration was less than 10(-4)% of the total content of the RNA.

The effect of tetrahydrofuran as solvent on matrix-assisted laser desorption/ionization and electrospray ionization mass spectra of functional polystyrenes.

It is demonstrated that tetrahydrofuran (THF) should be used with caution as a solvent in polymer sample preparation for matrix-assisted laser desorption/ionization (MALDI) analyses. The presence of peroxides in THF may cause the oxidation of chemically active groups. This effect is illustrated in the case of S-containing polystyrene derivatives.