In Vitro Selection of RNA Ribonucleotides Reductases: Separation using Boronate Affinity Chromatography. 
Kareem Shehab 
Faculty Advisor: W. Reef Hardy

     While modern organisms carry the genetic code in the form of DNA, transcribe the code into mRNA, and express the code as protein (which involves rRNA and tRNA), it is thought that RNA both carried the genetic code and carried out important biochemical transformations in the prebiotic world. Indeed, the discovery and characterization of RNA polymers with catalytic activity (ribozymes) is evidence to support the claim that long ago our world was RNA-based. It is also known that deoxyribonucleotides are generated by the reduction of ribonucleotides by a class of enzymes called ribonucleotide reductases. If we assume that the ancient world was in fact RNA-based, we are presented with a paradox. If DNA codes for protein, but an enzyme is required to generate DNA, which came first? It is possible that a ribozyme catalyzed the reduction of RNA nucleotides to DNA, and using in vitro selection, we explore that possibility.

Support provided by: Howard Hughes Medical Institute