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Purine is a heterocyclic aromatic organic compound that consists of two rings (pyrimidine and imidazole) fused together. It is water-soluble. Purine also gives its name to the wider class of molecules, purines, which include substituted purines and their tautomers. They are the most widely occurring nitrogen-containing heterocycles in nature. [1]
These purine-pyrimidine pairs, which are called base complements, connect the two strands of the helix and are often compared to the rungs of a ladder. Only pairing purine with pyrimidine ensures a constant width for the DNA. The A–T pairing is based on two hydrogen bonds, while the C–G pairing is based on three.
Pyrimidine (C 4 H 4 N 2; / p ɪ ˈ r ɪ. m ɪ ˌ d iː n, p aɪ ˈ r ɪ. m ɪ ˌ d iː n /) is an aromatic, heterocyclic, organic compound similar to pyridine (C 5 H 5 N). [3] One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring.
RNA is composed of purine and pyrimidine nucleotides, both of which are necessary for reliable information transfer, and thus Darwinian evolution. Becker et al. showed how pyrimidine nucleosides can be synthesized from small molecules and ribose, driven solely by wet-dry cycles. [10] Purine nucleosides can be synthesized by a similar pathway.
Examples of non-basic nitrogen-containing aromatic rings are pyrrole and indole. Pyrrole contains a lone pair that is part of the pi-conjugated system, so it is not available to deprotonate an acidic proton. [1] The basic aromatic rings purines and pyrimidines are nucleobases found in DNA and RNA.
The secondary structure is responsible for the shape that the nucleic acid assumes. The bases in the DNA are classified as purines and pyrimidines. The purines are adenine and guanine. Purines consist of a double ring structure, a six-membered and a five-membered ring containing nitrogen. The pyrimidines are cytosine and thymine. It has a ...
Illustration of a transversion: each of the 8 nucleotide changes between a purine and a pyrimidine (in red). The 4 other changes are transitions (in blue).. Transversion, in molecular biology, refers to a point mutation in DNA in which a single (two ring) purine (A or G) is changed for a (one ring) pyrimidine (T or C), or vice versa. [1]
Purine analogues are antimetabolites that mimic the structure of metabolic purines. Examples