Preliminary characterization of crystals of an in vitro evolved cyanocobalamin (vitamin B12) binding RNA

A 35-nucleotide pseudoknot that binds vitamin B-12 been isolated using systematic evolution of ligands by exponential enrichment (SELEX). Affinity chromatography was used to purify functional, properly folded molecules and the hanging-drop vapor-diffusion method was used to crystallize this aptamer. Two crystal forms have been obtained and the preliminary crystallographic characterization is reported here. Both crystal forms (space groups I222 or I2(1)2(1)2(1) and C222(1)) diffract to 2.9 Angstrom and should prove sufficient for structure determination.