USE OF LOW-MOLECULAR-WEIGHT POLYETHYLENE-GLYCOL IN THE CRYSTALLIZATION OF RNA OLIGOMERS

We have crystallized a variety of RNA oligonucleotides in a form suita ble for X-ray diffraction studies using polyethylene glycol with a low -molecular-weight distribution (PEG 400) as the precipitant. Crystalli zation experiments on a set of 26 RNA oligomers ranging from eight to 12 nucleotides in length resulted in eight diffraction-quality crystal s. Of these eight RNA crystals, six utilized PEG 400 as the precipitat ing agent. We have also been able to obtain large single crystals of a DNA-RNA hybrid, transfer RNA (two different conditions) and a catalyt ic RNA from PEG 400 solutions. These results suggest that PEG 400 may be a generally useful alternative to 2-methyl-2,4-pentanediol (MPD) wh ich has, thus far, been the most successful precipitant for DNA oligom ers.