Tautomerism

Tautomerism

	Tautomerism - The ability of a molecule to exist in more than one chemical form is called tautomerism .All the four common bases of DNA (adenine, guanine, cytosine and thymine) have unusual tautomeric forms, which are, however, rare. The normal bases of DNA are usually present in the keto form. As a result of tautomeric rearrangement they can be momentarily transformed into the rare enol form in which the distribution of electrons is slightly different.
Normal base pairing in DNA is A-T and G-C. The tautomeric forms are, however, capable of unusual ('forbidden') base pairing like T-G, G-T, C-A and A-C
This unusual base pairing results in misreplication of the DNA strand, giving rise to mutants in some of the progeny. Thus A*, a rare tautomer of adenine (a) pairs with cytosine. This leads to G-C pairing in the next generation. Spontaneous mutations can also arise as a result of ambiguity of base pairing during replication because of 'wobble'

	Back to Home
Suppressor Genes Frameshift Suppressions Molecular Basis of Mutations Spontaneous Mutations Tautomerism Induced Mutations Chemical Mutagens Base Analogues Agents Modifying Purines and Pyrimidines OR Agents Labilize the Bases Agents Producing Distortions in DNA Radiations Types of Mutations