Peptide Nucleic Acid

dnaWhat is a Peptide Nucleic Acid? The name is self suggestive. One can easily deduce that the molecule must be a combination of a peptide and a nucleic acid.Well, for all practical purposes that is exactly what it is. A Peptide Nucleic Acid or a PNA is a synthetic molecule that is a nucleic acid analogue or a structural mimic. A natural nucleic acid (DNA or RNA) has a sugar phosphate backbone linking together the nucleotide bases. In a PNA, the nucleotides are retained, but the charged Sugar phosphate bridges are replaced with a synthetic peptide backbone that is usually composed of N-(2-amin-ethyl)-glycine units. This modification yields an uncharged and a chiral molecule, which follows the rules of the Watson and Crick base pairing as faithfully as its Nucleic acid cousin. In addition, PNA now becomes resistant to enzymatic degradation and exhibits increased thermal and ionic tolerance. Now, the PNA due to its unique structural features can recognise DNA and RNA in a sequence-specific manner. Also what is most interesting is that it recognises duplex DNA, and binds to it by strand invasion forming a triplex PNA-DNA-PNA.This form is extremely stable. Any student of Biotechnology would have by now grasped the immense significance of this molecule with respect to its Pharmacological and Diagnostic abilities. It is the tremendous versatility and the potential of this molecule that brings it into focus in this week’s Cutting Edge.

fig-pnastru

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