ABSTRACT
The demand of the scientific community for synthetic oligonucleotides has grown exponentially over the past decade. Fortunately, the abundant source of DNA oligonucleotide primers has satisfied the tremendous needs of the genome sequencing efforts, functional genomics, or other polymerase chain reaction (PCR)-based detection methods. Oligonucleotides also have widespread use in the development of therapeutics and diagnostic applications, including chip-based DNA microarrays. Significant advances in structural biology and biochemistry have been achieved through concomitant advances in DNA and RNA chemistry. For instance, the current state of the art in ribozyme research, including crystal structures, would not have been possible without the accompanying improvements in RNA synthesis. Research on the many roles of nucleic acids has, in the past, been hindered by limited means of producing such biologically relevant molecules (1-4]. Although enzymatic methods existed, protocols that allowed one to probe structurefunction relationships were limited. Only uniform postsynthetic chemical modification (5] or site-directed mutagenesis [6] was available. Fortunately, oligonucleotide synthesis by the phosphoramidite method has greatly increased our understanding of DNA and RNA. Site-specific introduction of modified nucleotides at any position in a given oligonucleotide has now become routine, allowing easy chemical probing of define functionalities.
