91Ó°ÊÓ

Nucleic acid constitute a long chain polymeric molecule where the monomer is termed nucleotide and the nucleic acids are termed polynucleotides. The major types of nucleic acids include DNA and RNA.

The most common ribose conformations are termed C3’-endo and C2’-endo. The term endo suggests that the displaced atom is on the same side of the ring as C5’. The term exo suggests that the displaced atom is on the opposite side of the ring from C5’.

The ribose pucker is primarily important in nucleic acids as it relates the relative orientations of the phosphate substituent to each ribose residue. The B-DNA comprises the C2’-endo conformation and the A-DNA is C3’-endo. In Z-DNA, the purine nucleotides are C3’-endo and the pyrimidine nucleotides are C2’-endo.