What are tautomeric forms?
Tautomers are isomers of a compound which differ only in the position of the protons and electrons. The carbon skeleton of the compound is unchanged. A reaction which involves simple proton transfer in an intramolecular fashion is called a tautomerism.
What is a tautomeric form of a base?
Tautomers are structural isomers that differ from one another based on the position of proton(s) and double bonds (Antonov 2014). The presence of multiple tautomers is expected to increase the structural and chemical diversity of nucleic acid bases, as shown in Figure 1.
What is a tautomeric shift?
The spontaneous isomerization of a nitrogen base to an alternative hydrogen-bonding form, possibly resulting in a mutation. Reversible shifts of proton position in a molecule.
How many tautomers are possible in purine?
Nine prototropic tautomers are thus possible for purine, four NH tautomers with the labile proton at N atom (N1H, N3H, N7H, or N9H) and five CH tautomers with the labile proton at C atom (C2H, C4H, C5H, C6H, or C8H) [20]. Their amounts in the tautomeric mixture strongly depend on environment.
What are the different types of purines and pyrimidines?
1 Adenine = 6-amino purine 2 Guanine = 2-amino-6-oxy purine 3 Hypoxanthine = 6-oxy purine 4 Xanthine = 2,6-dioxy purine
Where are the amino atoms found in purine?
Generally, two nitrogenous bases in the DNA and RNA are found to contain purine rings Adenine which is known as 6-aminopurine Guanine, which is known as 6-oxy-2-amonipurine The amino group in Adenine is present at the C6 position (carbon atom present at the 6th position of the ring).
What kind of rings are in a purine?
Purines are generally organic compounds consisting of two aromatic heterocyclic rings. They are usually water-soluble and contains nitrogen and carbon atoms in their rings. Hence they are known as heterocyclic. They are broadly classified into normal purines, substituted purines and tautomeric purines.
Which is the most common form of tautomerization?
Keto-enol -tautomerism is the most common form of tautomerism and occurs in aldehydes, ketones and related compounds (essentially carbonyl compounds with one or more hydrogens on the α-carbon). Example: 2,4-pentanedione in equilibrium with the corresponding enol, in water are approximately 84% ketone and 16% as the enol.
