Interactions between photoswitches and nucleic acids and the selection of nucleotide synthase ribozymes

The RNA World hypothesis suggests prebiotic enzymes were RNA molecules (ribozymes) rather than proteins. Previously, in vitro selection identified a ribozyme that synthesized the glycosidic bond in a pyrimidine nucleotide. A selection to minimize size and increase catalytic efficiency was concluded and kinetic behaviour of one isolate was examined. In preparation for two new selections for purine and pyridine nucleotide synthase ribozymes, constructs representing theoretical end products were synthesized and used to test the feasibility of the selective procedure. Dithienylethenes are molecules that interconvert between two isomers (each with unique properties) in response to different light stimuli. It was our interest to control DNA binding and RNA cleavage abilities of novel switches by light exposure. One switch successfully bound DNA, with each isomer displaying the same association constant. Another project featured a histidinefunctionalized switch to mimic RNase A. However, no significant difference in cleavage was observed between the two isomers.